REVIEW: [RRS] Retractable Ruby Sharpener


Flashlight Enthusiast
Jul 5, 2012
hope you like(?) the idea, one look's worth a thousand words:

The pen-style retractable ruby is an inexpensive high-feedback sharpener most suitable for macro-/micro-deburring and because of its wondrous efficiency a powerful must-have item in anyone's sharpening arsenal, not only in one's portable kit. Hand-held white or gray cylindrical (or conical) ceramic rod/stick/file sharpeners, or pen-style sharpeners, exist on the market for ages, they have been acknowledged and successful, e.g. the popular pen-style Victorinox Dual-Knife Sharpener (43323). What makes this diy variant —let's code-name it "RRS"— special is the extreme fineness, effectiveness, tactile feedback, and cost of replacement (if drop'n cracked).


  • Fineness: almost as fine as the Spyderco 204F. My unit could very well match the advertised "3000 grit" rating! The surface quality is very dense/smooth and homogeneous, flawless, unicolor, and finer(!) than any other CN ruby i had before! It leaves a metal finish similar to that by a Spyderco Fine (204F) stone, i.e. barely falling short of a 204UF mirror-polish. And who didn't ever want a Vinox pen-style sharpener with very fine ceramics?
  • Effectiveness: not only in my experience, ruby stones are notably more effective at removing burr. One can start with edge-trailing movements but ultimately do edge-leading movements to shear off any kind of burr. Of course, it is also possible to sharpen with the RRS and create a burr.
  • Feedback: holding the item loosely in the left hand (LH) in horizontal orientation makes the LH more sensitive to tactile feedback. The RH, holding the blade equally loosely, receives lots of useful feedback: drag the blade slowly, with little pressure, at same or slightly higher bevel angle, from heel to tip (or from tip to heel) across the dry ruby, and especially during edge-leading movements the RH can feel higher resistance when the burr gets sheared off. One could not feel such a difference, if the stone weren't that fine! The LH can hold the item so loosely because of the item's light weight, slim form factor, and secure length; the holder weighs practically nothing, so all stone feedback gets transferred to the LH in pure form. Holding loosely also helps controlling the pressure between stone and bevel.
  • Cost of Replacement: it's worth mentioning that the ruby costs only 1-3$ shipped, depending. US stock might be running low, so if you do find a good source and like the product, it'd make sense to order a spare (in case you drop'n break one).

  • Things can break, if you drop them on hard floor. That's generally true for most of our stuff! The ceramic rod could break inside the aluminum holder, if dropped on bathroom tiled floor from 3 feet (the Vinox ceramics probably wouldn't break with such a drop). If all fails, the cost of replacement is low.
  • Shoppers might run into problems of availability and lottery. I ordered from AX and received better-than-expected quality, while packaging was poor; maybe i was lucky, or maybe the current AX production batch of Ø6mm is like that: flawless. Bezos platform might be running low on stock of the required 6mm-diameter. Is it lottery/gamble to receive a flawless unbroken unit? I doht know. A con for shoppers, not for owners of a flawless unit.

TL;DR — Suitable for:
+ readers who have experience with ceramic rods, croc sticks, portable sharpening, pen-style sharpeners, Spyderco Sharpmaker, or similar
+ readers who own blades with recurved parts (concave blade sections)
+ readers who have problems with deburring
+ readers who are sharpening beginners and/or on a tight budget
+ readers who are curious to experience the power of a high quality sintered ruby ceramic whetstone (in comparison to other ceramics)

In the following, some more pics and accompanying blahblah text … :sweat:

The made-in-chinas sintered ruby cylindrical stick came unharmed in a bubble-padded shipping envelope with no further protection like cardboard, styrofoam or whatever. Maybe it is fortunate that i had ordered just one piece because two pieces would have banged against each other inside the envelope and could have caused chips and cracks. Furthermore i had reason to fear that the package wouldn't contain the correct diameter. After some 3.5 weeks between order day and delivery day i was fully relieved: the package didn't get lost during transit, the item arrived unbroken, the item had the correct diameter of Ø6.0mm, and the item was in better-than-expected quality:

Wait, where is the holder? Probably you have it already in your garage, it is a ubiquitous thingy, search term <retractable sharpening> on Jeff Bezos platform, the auction platform, or in your preferred local hardware store. I made a Ø6mm-plug out of an old eraser to stop the ruby from sliding inside the holder during storage/transportation, and i added an easy-to-remove wrist strap to secure the product to my loosely holding LH:

Before we get to the fitment/assembly of the RRS, let's have a look at the stone quality in comparison to my other rubies from 5 similar viewing angles:

I will say that the color of the cylindrical ruby is very similar to, i.e. pretty much the same as the other 2 CN rubies, as you can see (short stone at top of pic, long stone at bottom):

The long stone, mine marketed by ANSELF brand for use with Ruixin Pro III, has amazing quality and properties for itself but the surface quality of the cylindrical ruby is even higher, and finer - by direct comparison i knew that i had to be satisfied with the delivered cylindrical ruby and that i couldn't have asked for more:

The left small stone ("DoubleStuff") has a meh surface quality, one could even tell from the photos. If all CN doublestuffstones have this identical quality, then i would probably not recommend it to other shoppers:

Personally I still find the CN doublestuffstone useful for some rough grinding/sharpening/deburring of tools or old knives. You can see machining marks on the ANSELF stone and none on the cylindrical stone:

Oh and the darker red ruby stone in the middle of the photos is the DD57F 100x6x3mm stone (Degussit Fine dist. Gesswein 35-2203, ~80$ shipped within US); DD57F is a tad finer than 204UF and, of course, superior to the CN cylindrical ruby (not that it matters though).

Now it's time to understand the fitment. Please find all relevant measurements from the photo. In particular, learn that the Ø6.0mm cannot be fastened by the collar lock, without mod. Imho the optimal locking diameter would be anything between 6.5-6.8mm, so the provided diamond rod with ~Ø6.25mm doesn't even fall into that optimal range lol:

The blue tube seems to have an inner diameter (ID) of ~6.9mm (hey hard to measure, right!?). I cut a 90mm long piece of thick tape (left-overs from a book protection roll, i.e. inoffensive nonaggressive adhesive) and wrapped it around one ruby end to approach that measure:

Instead of book tape one could find/use other media to enlarge the diameter from 6.0mm to ~6.8mm, for example paper, label paper, rubber, plastic, scotch tape, etc. After some time the tape must be renewed anyway because of moist or oil creeping in. This photo explains it well:

Enlarged to Ø6.8mm and with a fully tightened collar, the ruby rod is seated firmly, without any much wiggle, in the holder. You get about 90mm (of the 100mm) of ruby use for comfortable sharpening/deburring, which is more than the original diamond rod!
(see photo again at top of the thread lol)

For storing inside the holder, i insert the rod upside down, and tighten the collar with an inserted the diy-made plug, for rattle-free storage:

I love the RRS product, so i keep it in an Olight carry case within direct reach. The diamond rod can be used without the blue holder; after sharpening two knives with it the diamond rod was fully broken in: it is finer than expected and i like it FWIW. Also great as general file (finger nails, wood, etc), not only for sharpening blades. Great to have:

The RRS is phuntastique stuff! Portable sharpening (and tabletop deburring) just got easier and funner!

The End. Hope you enjoyed reading/looking or the idea (actually not my original idea, i saw 1 AX customer review doing it and wanted to try it out for myself, knowing about the power of my ruby stones, and it's a bullseye of a method!). Hopefully i could inspire some readers to follow this example. Please report once you got your own RRS. For me, the story doesn't end here. I am so stoked about this incredibly fine ceramic pen-style sharpener that I'm looking at the cylindrical Degussit Fine …


Flashlight Enthusiast
Jan 27, 2017
Dirty Dirty South
Thanks for the write up! Any idea what the hardness of this material is relative to ceramics, aluminum oxide or other sharpening abrasives?


Flashlight Enthusiast
Jul 5, 2012
Summary of this post:
I've checked out the two geman asin's (sold by different CN sellers, shipped by Amzn Prime from amzn DE warehouse fulfillment center), their ruby stones stem both from the "Rehoo" (or "Ruihe", "Rohee" depending on your chin. lang.) factory, and the stone quality is notably lower than my AX stone (presumably from Golden Peak factory), and for the sake/purpose of this thread i would not recommend them (AVOID) because the quality fluctuations between delivered units make the Rehoo stuff definitely a disappointing lottery. In other news, a fellow geman boardie discovered a different build of a RRS (in silver color :kiss:), using an inexpensive yet high value so-called "clutch pencil (5.6mm lead holder)". I tried his solution (for confirmation), and i like it very much, thanks! The silver RRS has cool advantages over my original "blue RRS", and i'll be using both RRS's. Time will tell, if i end up using the silver more frequently than the blue; i really might!

Let's talk about the silver RRS first (~10€ in DE). It has an all-metal construction (stainless clutch, brass tube, silver-painted aluminum housing), i added a pair of o-rings to reduce scratchiness and rattle of the stainless push button against the housing, it works:

Confirmed working models are the Koh-I-Noor K5340 (e.g. in silver color) and the K5311 (available in black color only, comes with a pocket clip). The silver is designed to hold 120x5.6mm leads, the black is for 80x5.6mm leads; fortunately the pencils are long enough to completely host our 100x6.0mm ceramic (even if your maths doesn't add up). The two models have in common that their clutch is made out of 6 thin flexible claws (clutch type1), which is key, whereas the popular K5347 and the mechanical pencil K5460 have 4 thick stiff claws (clutch type0):

You'll find many nice 5.6mm models in the kohinoor catalog which fulfil the clutch type1 requirement, so feel free to pick your favorite model in your favorite color, with plastic body or aluminum body, with pocket clip or without pocket clip. I am very pleased with the silver (long length, not the heaviest weight, looks/feel of a tool, symmetric ergonomic design, all metal construction, metal female/male threads, robust/unbreakable); it does lack a pocket clip though, and i choose to live/work without it because etc.

Attention. Out of the box, depending on the exact diameter of your ruby rod sample (e.g. 5.90mm, 5.92mm, 5.96mm, or similar) AND the manufacturing tolerances of your kohinoor sample, the rod might not fit through at first and it'd cost you some efforts to overcome the surface roughness at the "bottleneck" (if your sample has one), where the stainless clutch meets the brass tube:

The brass tube seems to have a slightly larger inner diameter (~ID6.3mm) than the stainless clutch (~ID6.1mm), so a potential bottleneck could be right at the (welded/soldered?) link of the two parts.

If you're so unlucky with the fitment that you can't twist/push the ruby rod past the soldering point, then feel free to try your luck with other kohinoor production units (of K5340 again, or K5311, or similar kohinoor models). If all fails, we know that it would be matter of seconds to clear the link with a manual/hand drill (6.0mm through-hole). Just saying, in principle the Ø6mm ruby rods are a great match for those two kohinoor models, and after mirror-polishing the 'inner diameter' (=the inside wall) with the ruby, all my rubies slide in and out without resistance/friction!
(youtube demo)

It's a pity that the attractive K5460, which works like a standard mechanical pencil, can't be used at all, here the maths add up:

The max usable ruby length of the silver is only a little less than that of the blue, while there is absolutely no concern about the security. Both RRS models hold the rod in position, with no wiggle, very very firmly, absolutely secure:

The silver has the advantage that the ruby retracts and auto-fixes to any (short) length. The silver weighs almost double and has a wider diameter to hold on to. It doesn't feel heavy or heavy-ish but i will let you know about my long-term experience of handling the bigger RRS (i haven't done any sharpening with it yet). Both the silver and the blue are all-metal constructions. There are many kohinoor models with plastic bodies (they are lighter and feel warmer) but i doht like the plastic threads on them:

Your local stationery shop sells kohinoor clutch pencils as bulk item, my amzn order came with a hard plastic case. The included lead is standard with pencils:

I'll keep the case, it's made out of thick plastic and stores the pencil sharpening tool neatly, protecting it's silver finish the from scratches:

Now it's time to talk about the Amzn stones (as opposed to my AX stone):

In the following series of stone pics i've used a loupe to get macro shots at low lighting, sorry for the poor pic quality and distorsions. Right off the bat, all(!) Ø8mm units were medium or coarse-ish, far from fine:

Other than that, the above set looks pretty decent, don't you think? Someone must have cherry-picked the bouquet because a random delivered Rehoo box contains flawed units as well.
If i'm not mistaken, the following photo showse all the Ø8mm ones. Counting from left, no.1 has circular micro ridges (ripples), i.e. perpendicular to the axis orientation; not smooth. The other four are texture-less, i.e. kinda smooth, but the fineness is medium towards coarse. If i need to grind and reprofile a recurved blade section, i'd do with this stone:

The Ø4mm units have surface qualities all over the place too. They are not masterfully manufactured. If you want to grind with them, they'd do the trick, sure:

The Ø10mm isn't much better. 4 out of 5 units weren't flawless: the two darker red rubies were coarser in some way (e.g. aforementioned ripples), the no.3 had a visible small area of finish defect (can you spot it?), and one had a tiny chip at the edge. The three pink rubies are aiming at a fine fineness but aren't really close to the 3000 grit of my AX unit:

Here another shot, with more realistic coloring. I expect these rods to perform like a 204M with regard to fineness (i'll report eventually):

And now the finale, the climax, the Ø6mm we've been waiting for.

Let's make it a quiz. You tell me which of the six units looks (=is) the finest, i.e. smoothest with highest grit rating (they're all advertised as "3000 grit" lol). The number of dots is for identification, here are ID1 and ID2:

Here are ID3 and ID4:

And here are ID5 and ID6:

I can see four different grades of surface fineness! Here a shot with all six units together. Counting ID's from right to left. The camera focus (sharpness) is to the right (ID1-3):

The camera focus (sharpness) is to the left (ID4-6):

Clearly, the AX unit is the finest, by a notable margin. Its beautiful fineness is why i feel so motivated. Good to know that amzn isn't the right place for sourcing that special quality rod. I understand that most readers doht want to wait 3-4 weeks for a 2$-paid item to arrive but maybe that's currently the only way to obtain the (Golden Peak?) quality. There'd still be some lottery involved, i guess, even if one ordered the identical AX item number.

When i have news/updates regarding cylindrical ruby rods (chinese or geman or else) or my continued use/experience of the RRS products, i'll report here (in my review thread, as i always do), so stay tuned/follow/subscribe/watch the thread. :poof:
Maybe someone does a short youtube clip on the topic. In any case, the RRS is my secret weapon in the sharpening arsenal. Really fun and effective. It's like a Sieger Long Life (dist. Böker, Boker, Westmark, etc) for pocket-carry.
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Flashlight Enthusiast
Jul 5, 2012
Any idea what the hardness of this material is relative to ceramics, aluminum oxide or other sharpening abrasives?
ruby is aluminum oxide ceramics with Chromeoxide additives, manufactured to higher mass density. thus your typical ruby stone is harder than Spyderco brown and white ceramics. the geman factory measures in absolute figures "23 GPa (Knoop, 100g)" or "1660 HV1" or "~200 HRC" (do we have absolute figures for Spyderco ceramics?).

ruby is basically the hardest endconsumer-commercially available ceramics on the market.
it is harder than white ceramics, harder than aluminum oxide.
diamonds are harder.


Flashlight Enthusiast
Jul 5, 2012
Which are the advantages/disadvantages of the blue vs. the silver, which one is preferrable?

1) silver during storage: Someone could press the attractive button and by accident release the ruby in its entirety, such that it drop'n cracks on the floor. actually one could make a diy rubber plug which would prevent accidental releases by third-party someones.
1) blue during storage: Someone loses/removes the diy plug and by accident loses the out-sliding ruby (attention!), such that it drop'n cracks on the floor.

2) in storage, the silver has double-wall protection and therefore should(?) have better drop impact resistance than the blue to protect the ruby from breaking/cracking inside the holder. one could reduce the shock impact by installing one pair of rubber bands, rubber rings, shrink tubing, or several layers of tape lol.

3) the silver is very practical and fun to deploy: you press a button (which is always a fun thing!), let the ruby fall out into your palm/desktop to perfect usable length (anything between 1-90mm), release the button and you're good to go. Very fast! For storage, or even as temporary precaution, you flip the silver upside down and press the button to let the ruby vanish inside the holder. Again very fast!
3) the deployment/storage of the blue is also fun but requires minimal patience, care, and calm finger work. not good in a fast nervous environment setting: you might be inclined to accidentally drop the ruby on the floor and break it.

4) the blue is much slimmer, much lighter. for the intended RRS purpose (=high-feedback/high sensitivity deburring) that's an advantage! the balance feels interesting, top-heavy.
4) the silver's total weight is absolutely okay. you get a nicely long holder in return, with improved balance.

5) the blue's finish is as slippery as the silver's finish. that's a tie.

6) the blue has a clip where a freewheeling wrist strap (or lanyard) can be attached for extra security.
6) the silver has no clip but other ruby-compatible kohinoor models with clip exist (e.g. K5311). if i need the extra security and lower weight for certain blade types, then i'll use the blue, done.

7) the silver comes with a plastic jewel case for neat storage.
7) the blue is more portable, suitable for RL carry (again, attention with the diy plug!),

8 ) the blue can be cleaned with a long Q-tip only; you're not supposed to remove the black plastic end cap.
8 ) the silver can be cleaned more thoroughly/easily by unscrewing the stainless end cap: you can look through the 6mm through-hole!

9) the blue costs 2.xxUS$ shipped if sourced from overseas, very cheap.
9) the silver costs at least 9€ shipped, which i find inexpensive for the great quality you get.

10) with the blue, the tape on the ruby must be renewed every so often, because oil does get in between the layers and degrades the adhesiveness.
10) with the silver, no tape is needed.

If it were for the intended RRS purpose only, then the blue would be the better choice; it also comes with a clip, and odds are high that readers own such a holder already. Owning both holders, i enjoy the premium feel and cool deployment more on the silver, so it's become my personal preferred choice in-house. If i were to go on a field trip and wanted to carry a portable sharpener (in my pocket, pouch, or backpack), i'd take the blue with me, for sure (the diy plug isn't very secure, unfortunately). However if i were a professional workman, mechanic, craftsman, i'd have the silver in my toolbox. both items are great value stuff and one could afford to buy them both if you like the concept of RRS.

Here a simple mod by adding some padded tape as drop impact absorbers and using the included jewel case white plastic spacer as stop for a freewheeling wrist strap (if i wanted to attach one for the sharpening session). The total weight of the tool is now 48g (w/o a strap), including the 10g weight of the chinese ruby:

The white plastic spacer also serves as super effective roll-away-protection! The mod makes the silver RRS less slippery, even without a strap. Obviously it would be very easy to undo the mod. Ideas Worth Spreading:

Typically i wouldn't use the silver with a strap though, because i do the sharpening/deburring on top of my office desk, holding the silver horizontally in my left hand. If the 48g tool ever slipped out of my left hand, it would only crash onto the desktop (not onto the tiled floor). With no harm done. Without a strap, i'd push the white plastic spacer to the front, touching the red tape; this way the white plastic works as finger guard/protection (left index, left thumb) during sharpening.

But it is good to know that i could attach a strap, if i had good reasons to do so. Meanwhile I'll leave the MecArmy strap on the blue.

I just made a diy plug out of an old eraser/rubber for the silver as a fail-safe during storage, e.g. when a third-party someone accidentally presses the button of the clutch pencil (lead holder): normally, the lead would fall out, drop on the floor, sh*t happens. With the installed storage plug, pressing the button will neither let the ruby nor the plug fall out, because the rubber is still held in place even with an opened mouth clutch! The stainless claws still grab/bite into the soft rubber. One needs to pull the plug out with some finger force (attention as always!). The plug is decent protection against ignorant button-pressers:

The nominal diameter of the plug is Ø7mm because that's how i carved it with the help of the aluminum cap. Just twist a piece of an old eraser against the cap and outcomes a cylindrical eraser plug:

Alternatively, you could just buy a cylindrical eraser such as the Staedtler 52855, which has the nominal dimensions of 97x7mm:

The Ø7.0mm diameter of the Staedtler is a little too thick argh (and tbh I should have tried the Ecobra 760321 with its Ø6.8mm first!), easy mod:

Yeah i like the new eraser material better, quite the beaut:

CAUTION AGAIN: The critical moment is when you remove the plug! The Staedtler plug is secure. But when you remove it, that's when the ceramic could/can/will fall out, if you don't hold the tool horizontally or upside down. So be fully attentive, conscious and careful, when/how you press the button or remove the plug!! Think of the ruby (not of the plug) when you remove the plug! 😲

EDIT2: I just sharpened 2 pocket knives with the silver, so fast so easy so straight-forward so without fail! I can reconfirm: my AX ruby is as fine as 204M, and the finest amzn ruby is coarser than 204M; great to have them both! The white plastic spacer not only serves as roll-away-protection on an inclined desktop but also as slip-away-protection in my left hand, while I balance the fully deployed tool. We always instruct beginners to "Use very little pressure when you try to deburr by edge-leading strokes!" but it's difficult for beginners to gauge how much pressure is being applied at the apex. With the silver, you can literally see the effect of the applied pressure:
  1. Open your left hand with the palm facing upwards. Let your left elbow rest on the desktop. Relax all muscles in the hand, and let the fingers auto-curl naturally.
  2. With your right hand, place the fully deployed tool horizontally in the left hand in such a way/orientation, as if the LH intended to stab something in front of you. The tool will lie across your relaxed hand, the left index finger touching the red tape, the other red tape being near the side of the hand. Let the white plastic spacer ride between the index and the middle finger; interestingly, its optimal location is around the balance point of the deployed tool!
  3. Don't close the fingers to grab the silver handle. Rather do the opposite: uncurl the fingers a little! Maybe form a 'valley' with the hand, with the tool being the straight 'creek'. The index finger will be rather stretched for better control of 'holding' the tool. Basically your relaxed hand is balance-supporting the tool, with the balance point (center of gravity) lying between the index and middle finger.
  4. Note that only very little pressure upon the ruby is needed to tip the balance over. Use this 'tipping pressure' for deburring the edge: do slow(!) edge-leading strokes on the ruby, you'll feel in either(!) hand when a burr gets sheared off, and you'll see(!) if you're applying too much pressure because the tool would start to tip over: reduce the pressure right away, in real-time, and continue with your edge-leading stroke! Your aim is to do deburring strokes while keeping the (unheld just supported) tool horizontal, i.e. in balance.
  5. When you're almost done, you could concentrate the deburring strokes near the end of the ruby rod to ensure that the very light pressure remains constant along the entire edge (cf. physics of a see-saw).
A picture is worth a thousand words, so i should post a photo here, hah.
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Flashlight Enthusiast
Jul 5, 2012
I sampled a few more rubies as spares, and the (lazy?) seller conceded that the sourced factory does offer differently spec'ed rubies but that she didn't mind 'the different shades of red color' of the cylindrical stones in her stock lol. Well that kinda confirms the lottery aspect of ordering cylindrical CN rubies from AX. This aspect must be off-putting for interested readers of the thread, sorry!

In my Ø6mm-CN ruby collection, i can distinguish 4 keeper grades of surface qualities (other grades should exist, and i'd return them), and i've ID'ed them thru number of white points:
  1. ruby No.1: the finest CN ruby one could get from AX; slightly finer than 204M
  2. ruby No.2: my original AX purchase from op. basically the same as No.1, due to production variances as fine as 204M
  3. ruby No.3: the best Rehoo ruby one could get from amzn; it's very okay but not nearly as fine as No.2/No.1. no need to have!
  4. ruby No.4: good to have a wear-resistant medium grit coarse-ish CN ruby for faster grinding
These keeper units have in common that their surface is smooth, homogeneous/uniform, regular, defect-free, ripple-free, etc, i.e.: flawless. The only difference is their fineness at performance (coarse/medium/fine). If you get your very first Ø6mm unit from a seller, you'll see/know right away if the unit is flawless or not. If it is, then it could be categorized as No.1, No.2, No.3, or No.4 — says me. You can then compare with 204M to learn which "number" you got.

No.1 performs very much like a brand-new 204M, or a tad finer. On the photo it does look finer, too. Used dry, the stone clogs fast and becomes even finer and starts producing a mirror-finish on knife bevels:

No.2 is essential the same as No.1. I would attribute the fact that it performs and looks slightly less fine than No.1 to production batch variances. Anyone who got a No.2 is a lottery winner:

No.3 was a keeper from my multiple amzn orders, the finest flawless unit, as documented earlier. In the photo, the surface quality looks similar to 204M but performancewise the Spyderco is much finer. It's maybe the kind of surface fineness for people who think that the 204M is too fine to begin with. The order didn't cost much at the time, so no complaints from my part:

No.4 is coarse-ish and similar to the diamond file from our blue RRS:

The (production) difference of surface quality/surface fineness between No.1 and No.2 is difficult to capture, they're basically the same stone quality:

Let's try again, another capture of No.1 vs No.2:

No.2 vs No.3, we've compared these two stones before:

No.3 vs No.4, oh yeah:

No.1 came coated OOTB, with some substanced smeared on it which made the surface look smoother, non-porous, shiny, finer, higher grit. Maybe some kind of cream, wax, glue, idunno. Here is a pic with two units of No.1, hope you can tell which is the untouched No.1 OOTB and which is the fully broken-in No.1, i.e. used/tested and afterwards scrubbed clean with Bar Keepers Friend:

Smearing some substance on the stone in order to raise the grit rating by 1000 or 2000 reminds me of the aforementioned clogging effect of our stones. I once suggested that we apply polishing compound on our ceramic benchstones but that's another story OT.

From bottom to top, two units of No.4's, one No.3 (for use in the blue RRS), one No.2, and two units of No.1's (one broken-in, one OOTB). With the right lighting and viewing angles some of the stones are quite sparkling, with the No.1's being the least sparkling:

Two more contributive posts are planned: one on Degussit 611 ruby ("ruby No.0", it beats the 204UF!), and one on my storage/carry solution for cylindrical rubies (or alternative ideas). I could also post my thoughts on pocket clips (does the silver need one?).
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Flashlight Enthusiast
Jul 5, 2012
señor 🤠 Rubí Dremel: This post is to show that the cylindrical rubies can be used successfully as 'holder' for finer abrasives (compound loaded surgical paper tape for use with dremel, or superfine sandpaper for manual use).

Today lemme talk slightly OT, about the usage of our round rubies for mirror polishing (in theory one could use wooden rods for this purpose too?), manual or motorized. I've been using this new mirror polishing technique extensively, with overwhelming success, so i can vouch for it and highly recommend it: yet another kreisl idea worth spreading! 🥳

The motivation is to polish in very tight/tiny spots, or "to dremelpolish" (=polishing by using a motorized rotary tool) without making a mess at your workplace. It is such a neat way of employing solid polishing compound with a dremel that one can do the dremelpolishing in an office environment; if you've ever tried dremelpolishing the conventional way, you'll know how fast and unavoidably the work environment gets messy with molten compound (paste particles!) flying around, argh: you'd have to wear a work coat, wear safety glasses, or work through an diy encasement to contain the flying particle contamination (~sand-blasting cabinet). As a precaution, one should always wear glasses when working with rotary tools! Anyway, this technique is very clean and neat, here it goes:

You load solid compound on surgical paper tape with as little oil as possible, wrap it around the Ø3.0mm (or Ø2.0mm) ruby in the correct wrapping direction at some chosen rod location, and then go about your business. One picture tells it all:

In detail. I store compound flakes/crumbs, scraped off my block of polishing compound(solid) with a piece of glass, in a small container. Distribute the dry flakes evenly just on the upper half (or third) of the paper tape which you have temporarily pseudo-stuck onto some non-stick backing paper. It is not necessary/not helpful to cover the entire paper tape area with compound. Rub the dry flakes into the tape. If really needed, place a dab (not a full drop!) of oil onto the tip of your index finger and then quickly rub over the dry flakes with it, just to help with the initial crack down of some stubborn solid crumbs. Note that during the dremelpolishing, the generated friction heat will dissolve your compound to paste(liquid) anyway, so we don't really want extra or excess oil in the paper tape:

For our small diameter rubies it is totally sufficient to cut short-length stripes like that:

Now it's your turn to decide where exactly on the long rod you want to place the paper tape wrap. Wrapped at the tip, you have deeper reach into the corners of your workpiece; the workpiece contacting point might be more prone to vibrational hopping, and the dremel will be louder because of the bigger momentum in the bearings. Wrapped near the shaft, the dremel runs calmer, less noisy, and you can exert more pressure on the contacting point; chances are higher that the rotating ruby tip touches your workpiece elsewhere by accident, so extra care of handling the tool is required:

Most dremels have one rotational direction only, my proxxon follows the right hand rule. Logically, the paper tape should be wrapped in the opposite direction. Of course, only the circumferential exterior, not the internal layers of tape will blacken by the abraded steel. It is not a good idea to cut off the blackened tape section and continue work with the remainder of the tape wrap, ask me why:

It is good advice to not wrap the tape tightly around the ruby rod. Fix the very start of the tape firmly on the ruby itself, yes. But when you complete the wrap, do so lightly, with no pressure, no tension, so that your wrap becomes soft, cushiony, provides some give. Feel free to replace the tape as frequently as you like. Mirror polishing with a dremel has never been neater, easier, funner, more satisfactory than with this technique:

Typically the paper tape on the ruby will just blacken during dremelpolishing, i.e. no mess, no flying particles, nothing. But if you dremel too hard against a sharp edge, the tape can get damaged (slowly) and it would result in a tiny hole in the exterior layer. At this point, a tiny shred of the (blackened) tape could fly off. Re-examining the first tape in the above photo (counting from the right), you could see the tiny hole and the black smear on the tape layer underneath. Once you notice that the tape got damaged during dremelpolishing, stop and exchange the tape, no problem. With more practice runs, your tape will just blacken and remain intact, as seen on the photo.

No doubt, one could load the paper tape with stuff like cheap CN diamond pastes instead (12 syringes for 4$ total shipped, down to 0.25micron? lol): experienced users who have been dremelpolishing with such liquid pastes before have now a good way of applying the paste to the dremel tool, ruby+tape+paste=ftw! Personally, for my reference mirror-polishing mini project, i use the ruby dremel with the white compound only, eliminating all micro scratches in the finish, leaving a decent mirror polish (just a bit hazy). Instead of following up with the manufacturer-recommended blue compound, i put the dremel/compounds/pastes away, and continue my mirror polishing efforts manually with broken_in SiC sandpaper, starting from P1200: i cut out a similarly small piece of sandpaper, attach it to the ruby rod (any preferred diameter!) with the help of a very thin stripe of double-sided tape (carpet tape), and then do manual rotating/sanding with it. In general, final balancing touches should not be done through dremelpolishing imho; from my experience, final balancing touches are always best done with superfine sandpaper.


Flashlight Enthusiast
Jul 5, 2012
Pocket clips. Here are a few thoughts on the presence/absence of a clip on the RRS:

There are a few matching/functioning Kohinoor models with clips like the popular shortish K5311 ("black RRS"). If the niece knocks my silver RRS with the stowed ceramic off the edge of the office table and it falls on the tiled floor, then the risk of ceramic breakage is the same as with the blue and black RRS; otherwise, I would think that the ceramic in the silver RRS might be better protected (double-walled: brass tubing, plus aluminum "silver" handle).

I use the clip on the blue RRS as attachment point for a wrist strap (security wristband/wristloop): while grinding with the blue RRS in my left hand, the tool can't accidentally crash to the ground, very good! Unfortunately, once you have the wrist loop on, it becomes a bit of a nuisance as soon as you are temporarily done with the grinding itself and need to walk around (to fetch something) or need your hands briefly for something else, like feeling the burr with your right thumb. In these two cases, you either keep the deployed tool in your left hand (left hand not free! letting the deployed tool dangle is unacceptable), or you put the tool out of your hand onto the desktop (left hand restricted movement or trapped within the table area), or you keep pulling the wrist strap off on off on off on for these two purposes (annoying). When deburring, you may need the flexibility/freedom to sometimes hold the tool in your left hand or in your right hand (annoying hand switch). When the tool lies unused on the table, its attached wrist strap can become a tripping hazard: fingers, hands, things and the like can accidentally get caught in it during the sharpening session and tear the tool off the table; in this regard, the wrist strap would be rather counterproductive as security construct.

On the positive side, the wrist strap does not interfere during grinding, it's a comfortable security construct.

Advantage without clip and without wrist strap: you can put the tool down immediately without anything still hanging on the wrist, and the constant tightening / putting on of the loop (e.g. when switching hands) is gone. In addition, the tool lying on the table cannot be accidentally pulled down from the table: entanglement not possible. In practice, imho one rather appreciates the unrestricted freedom of handling than the security against accidental drops.

If you choose a Kohinoor model with a clip, then you have the freedom to attach a freewheeling loop (i.e. a wrist strap with a freewheeling attachment location) or to let it be, all the power to you good for you :p. My silver RRS doesn't have a clip but it has that plastic spacer in the middle which helps to attach a freewheeling loop, if i wanted such a thing on it.

Well, I've been doing it this way:
my goto RRS is the silver (it's more fun/more practical), and i always hold it in my left hand: from that position, the worst it could do while grinding/deburring is crash onto the office desk or into my lap. Should I need to employ the RRS right-handed (e.g. for swords, lawnmower blades, sabers, axes, hatchets, sickles, scythes, i.e. where the chunky blade is stationary and the honing motion comes from the right tool hand, as in the case of a cello musician or violinist stroking the bow over the chunky instrument), I will use the super-light blue RRS with the loop attached, because the RRS is more likely to accidentally slip out of the right hand. In either hand, typically, the RRS is held very loose/weightless from the start to preserve the sensitivity in the hand (for feedback when deburring).

So the answer is: No, the silver RRS does not need a pocket clip for securing a wrist strap. Instead it has a plastic spacer in the middle which would serve such a purpose well enough, but in practice, i prefer to use it without a security wrist strap! The blue RRS needs such a thing, the silver RRS doesn't.

t: And what if i wanted to actually clip the silver RRS to my pocket?
k: Yeah right.


Flashlight Enthusiast
Jul 5, 2012
Spyderco round ceramic file. All i have to say about the 400F1R in this post.

My direct measurements of the ceramic rod, the diameter is Ø6.22mm, the length is 126.93mm, the weight is between 14-15g (on my +1g kitchen scale), so maybe around 14.5g to be more precise. With these data the mass density is around 3.76g/cm³ (which is higher than CN ruby and lower than geman ruby) but wtf cares about mass densities lol.

Amzn gemani delivers the product like this, file in a transparent plastic cylindrical container, bagged in a plastic zip bag:

Without the bag, the round container could roll off the desktop anytime, so I don't keep the ceramic file in there, see my other post on ceramic rod storage solution.

I marked the maximum retractable length in red, and the minimum recommended retractable length in green. When you insert the file in the silver RRS (we doht need to consider the blue RRS here guess why), you should retract to anywhere between the green and red line for a firm hold:

Can you see what i did there? I transferred all stickers to the Kohinoor case hehe. Btw, like a "flag", the installed red rubber plug on the silver RRS is also a visual reminder signalling me that the RRS is loaded with a ruby (not empty!). Without the plug, i wouldn't know for sure whether the silver is loaded or not. With the plug on, i know that the RRS is loaded and that it's safe to carry/being handled.

Would the file retract completely in the silver? Lengthwise yes it would but the Ø6.22mm diameter is 0.22mm too wide for the Ø6.0mm diameter of the internal bottleneck. There is no point in modding the bottleneck from 6.0 to 6.22, i am pleased that the silver can hold the file without further mods:

Performance. The 400F1R is finer than my RubyNo1. Not by much, not by a significant amount, but yes it is finer. There you have it. Congrats to Sal Glesser for bringing such a fine ceramic file to market at affordable pricing, i'm glad that i bought it, it improves my "Ø6mm collection" by a bit. Today i touched up the Berndes chef knife (incl. burr creation) with RubyNo1 and refined the edge with the 400F1R and didn't even have to think about microburr removal. That ceramics sequence took care of the micro deburring, and i got one of the sharpest freehanding results ever!

No, the 400F1R (clogged or not) does not leave a mirror polish, whereas a clogged RubyNo1 kinda does.

How does the Spyderco file compare to 204F and 204UF in terms of fineness?
Clearly, the 204UF is finer than 400F1R.
Gimme some time to detect an objective difference in fineness between 204F and 400F1R. However, for us, it's more important with which product you're able to achieve a sharper end result with more ease. My point being, it is easier to manipulate a knife edge with a light-weight round file clamped in a grippy silver holder than to handle the heavier slippery 1×204F in a similar fashion. I could claim that it is easier/faster to reach a super sharp crisp microburr-free apex with silver RRS (than with the 204F used in a conventional or unconventional way), then it really doesn't matter if, microscopically, the 204F were finer than the 400F1R. Objectively, 204F might be a tad finer .. i'll give my final observation ("yes/no/same") later — if i can figure it out.

5 more contributive posts are planned: one on Degussit ruby 6mm, one on Sieger Longlife ruby, one on 6mm strop, one on storage/carry solution for cylindrical rubies, and in distant future one on modding a 6mm ceramic rod with sandpaper.


Flashlight Enthusiast
May 8, 2017
Eastern Europe
One of my jeweler friends, when I threw him your sharpening topic, pointed out this link to me, says that they are very good stones. Have you tried them? He will send me some ruby files.

I climbed the site a little, it seems that this equipment is for jewelers, there are the same Kohinoor holders and there are similar to thinner mechanical pencils


Flashlight Enthusiast
Jul 5, 2012
Have you tried them? He will send me some ruby files.

I climbed the site a little, it seems that this equipment is for jewelers, there are the same Kohinoor holders and there are similar to thinner mechanical pencils
Thx for your interest!
I mentioned Gesswein before, and I am very familiar with their "DEGUSSIT®" ruby stones which are actually made in Mannheim factory gemani by Friatec/Frialit/Aliaxis now owned by Kyocera Japan. It's most likely the best commercially/industrially available ruby ceramics in the world, and very expensive and hard-to-buy in gemani if you're a private end consumer. Sharpening, deburring, finishing with degussit is actually my expensive secret weapon and i can't expect readers to get their hands on it too. It's much "cooler":cool: to get everyone set up with cheaper CN rubies which, with some AX lottery luck, achieve identical sharpness results.

The more experience one has in sharpening, the more one learns that reaching crazy sharpness by freehanding is 70% skill and only 30% the quality of your abrasive. The ruby No.2 from the op (the very first picture) has that quality, it's sufficient to get a blade hair-whittling sharp! Maybe that's the most powerful lesson to learn from the entire thread.

Don't believe me?

I am proud to present this video demonstrating hair-whittling directly after Spyderco Medium (from 21:35 on):

Obviously he has A+ skill level. My level is around B+, so having the best quality abrasives (like CN ruby No.1 and No.2, degussit ruby, Spyderco M/F/UF) lets me focus on the 70%, improving my skill. With the cylindrical ceramics, freehanding has become so much easier: less skill is needed, because it is easier to sharpen with RSS than with 302M.

I will show more photos of degussit rubies in near future but doht hold your breath because the post woht be important or interesting: whoever got hooked on RRS as main sharpening method like myself and got a ruby No.2 (with a kohinoor holder), will have learned by now to reach crazy sharpness just with such inexpensive stuff. Then there is no gain (in sharpness or else) by upgrading to expensive degussit! Realizing that, i did return my degussit Ø6mm to the distributor for a full refund.

The linked Gesswein pencil holders are for square abrasives, not cylindrical abrasives iirc. The whole point of RRS is that the abrasive is round so that your blade cannot cut into a ceramic edge. That's why Spyderco 204M has rounded edges, with R1 radiused (r = 1mm). The downside is that cylindrical abrasives are not optimal for straight edges or to keep them straight.:cool:
  • cylindrical abrasives (like RRS) => suitable for convex-shaped blades ("bellies") and for concave-shaped blades ("recurves"); not optimal for straight blades, i.e. for maintaining their straightness
  • flat abrasives (like benchstones) => suitable for straight blades and maintaining their straightness and for convex-shaped blades; absolutely impossible to sharpen concave-shaped blades!
The Spyderco Sharpmaker rods, having flats and having rounded edges, combine the two worlds, however their shortcomings are: they're heavy-ish, slippery in hands, not very portable, and they are friable (=get consumed). And beginners struggle to employ them successfully as deburring tool. Whoever loves the Sharpmaker rods, should appreciate the RRS!

Hope you @desert.snake can share your experience with the Gesswein ruby files (Degussit??) soon!! :buttrock:
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Flashlight Enthusiast
May 8, 2017
Eastern Europe
A couple of days ago I received files in the mail. They are all very hard and make a ringing sound like glass rods. I think if I drop them on the floor, they will split into small pieces, so I try to be careful. The smallest are really very small and are most likely needed by jewelers and watchmakers. Larger ones have round, oval, triangular, square and ribbon shapes. Only oval and round are suitable for sharpening a serrated blade, the rest I can most likely use only if I decide to make a filework on a knife. It's hard to say what roughness is here, but the metal gnaws quickly and the knife becomes sharper. Easy to clean with oil. So far I am satisfied, but I want to try a tapered rod for a serrated blade - 'Round, one end tapered' 100 x 5 x 2 mm, 901-41 255-0 and 903-44 255-0





Flashlight Enthusiast
Jul 5, 2012
Holy smokes, you got the original Degussit warez! 😍
Congrats to the acquisition!! 💪

Btw from my experience, the Degussit Fine is not as "chip-resistant" as i wanted to believe, talking of the edges. I modded my Quark Tool with the edges and .. 👻

I'll update the thread when i can. Got a bunch of photos of Degussit 6mm cylindrical, stay tuna, i.e. subscribe.
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Flashlight Enthusiast
May 8, 2017
Eastern Europe
Here are a couple of photos, I did not feel the cut by the serrator until I saw that my hands were somehow sticky and wet))) The semicircular file is too small for large teeth and too large for small teeth. At the same time, you can sharpen it, it will not look as beautiful as the factory sharpening, but it works. So I want to find a round tapered file







Flashlight Enthusiast
Jul 5, 2012
Thanks a lot for your contributions to the thread, highly appreciated!

Round tapered file, i.e. conical file, the only one which i have is the one from the RDS (retractable diamond sharpener). And I've used it a lot!
Afaik a conical ceramic file exist in Degussit material. My cylindrical ceramic files are 2mm, 3mm, 4mm, 6mm, 8mm, and 10mm in diameter. Good enough for the serrations i found on my knives.

If you sharpen serrations very rarely like i do, then i'd stop looking and simply move on. But do get the blue RDS from AliX, inexpensive stuff and totally worth the few bucks. The aluminum holder is cheap/thin but the rod is a long-lasting piece of equipment which everyone in the knife\sharpening hobby should have. imho. So useful, so powerful, so inexpensive. A no.1 no-brainer.