Help Identifying HDS Sapphire vs Glass lenses

RPC

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Can anyone offer observable characteristics of the HDS sapphire lens to help me differentiate a glass lens from a sapphire lens?
 

aznsx

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Can anyone offer observable characteristics of the HDS sapphire lens to help me differentiate a glass lens from a sapphire lens?

3-G's probably correct, but as a last resort idea if you don't come up with a solid answer, you might consider shooting an e-mail to the folks at Flashlightlens just to see if they have one. I don't know that they sell such lenses (likely not), but since they apparently know a thing or two about flashlight lenses they might happen to know the answer - if one exists.

Edit: If one could measure the index of refraction, that might differentiate non-destructively, but if so you'd already likely be into the 'costly test equipment' thing.
 
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RPC

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Appreciate all of the replies.

Heard back from Henry with guidance on differentiating between glass and sapphire, think I’m GTG.
 

aznsx

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Ahh, it is more scratch resistant. How is the light throughput compared to something like a UCL?
I can't vouch for the accuracy of this info, I just recall seeing it once fairly long ago when looking at something else:


This source says 'harder and more scratch resistant', but as pointed out above; when it comes to materials, often the hardest are the more brittle. Always tradeoffs and optimization / prioritization for purpose. No idea about the optical characteristics. From what I know, Borofloat's always seemed to be a good enough combination of characteristics and price EDIT: (they were a standard feature on many of my favorite lights - no extra charge) for a flashlight lens for my needs. They seem to do well, haven't noticed them getting scratched up, and haven't broken any (yet - shouldn't have said that).
 
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kaichu dento

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What are the advantages of a Sapphire lens?
Sapphire is much more durable than the alternatives.
Sapphire is more scratch resistant than glass but more brittle.
This urban myth just keeps going, but in all the years I've been bashing my sapphire crystal watches into things, none have ever broken.

When it comes to the lenses on my HDS lights, I've had scratches in a few of them, except the ones with sapphire lenses.
 

aznsx

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I can't vouch for the accuracy of this info, I just recall seeing it once fairly long ago when looking at something else:


This source says 'harder and more scratch resistant', but as pointed out above; when it comes to materials, often the hardest are the more brittle. Always tradeoffs and optimization / prioritization for purpose. No idea about the optical characteristics. From what I know, Borofloat's always seemed to be a good enough combination of characteristics and price EDIT: (they were a standard feature on many of my favorite lights - no extra charge) for a flashlight lens for my needs. They seem to do well, haven't noticed them getting scratched up, and haven't broken any (yet - shouldn't have said that).

How is the light throughput compared to something like a UCL?
I neglected to address this part, but my opinion based not on material science but rather purely from a marketing perspective, is:

Given that this is a very expensive part for a 'flashlight lens', that the purpose of a flashlight is to transmit light, and that those who market flashlight lenses do comparatively (numerically) rate them for light transmission, I think it's safe to assume that if optical characteristics were one of the 'selling points' / advantages of this part, that would be cited along with the two 'advantages' which are cited. Since it isn't, I would therefore assume it is likely no better than, if as good as, competitive lenses of Borofloat or one of its newer derivatives (like UCL v3, etc) in optical performance.

Back to that "purpose" part, I have little doubt that sapphire glass is the ideal watch crystal material, and that surface hardness / scratch resistance is a priority since they're most likely to get scratched. My highest priority for a flashlight lens however is resistance to thermal and physical shock. My flashlight is more likely to be subjected to falls or experience thermal stresses than for the lens to be scratched. Borofloat is field proven / time tested in terms of my highest personal flashlight priorities, and scratches would not appear to be an issue of concern on mine.
 

RPC

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I would be curious to know what Henry said.
Fair ask:

“The way to tell the difference between sapphire and glass is the color of the reflection from a light - noon day window light works or a 5k interior light. Unfortunately, the color has changed over time. Current sapphire lenses have a brownish reflection. Prior sapphire lenses had a bluish white reflection. Current glass lenses have a blush reflection while older glass lenses had a reddish reflection.

Henry.”

Henry: If you see this and don’t want it posted for any reason, LMK.
 

kaichu dento

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I have little doubt that sapphire glass is the ideal watch crystal material, and that surface hardness / scratch resistance is a priority since they're most likely to get scratched. My highest priority for a flashlight lens however is resistance to thermal and physical shock.
I've never broken any of my flashlight lenses, much less the sapphire ones and I doubt you'll ever be able to damage a sapphire lens installed in an HDS light without shooting straight into the reflector, which is not what most us would ever do.

I didn't previously care which lens my HDS had until I noticed that all the standard lens equipped lights ended up with scratch and abrasion marks on them.
 

LRJ88

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I've never broken any of my flashlight lenses, much less the sapphire ones and I doubt you'll ever be able to damage a sapphire lens installed in an HDS light without shooting straight into the reflector, which is not what most us would ever do.

I didn't previously care which lens my HDS had until I noticed that all the standard lens equipped lights ended up with scratch and abrasion marks on them.
And then there’s Hogo…
 

aznsx

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Sapphire is much more durable than the alternatives.

This urban myth just keeps going, but in all the years I've been bashing my sapphire crystal watches into things, none have ever broken.

When it comes to the lenses on my HDS lights, I've had scratches in a few of them, except the ones with sapphire lenses.

This might be where that "myth" came from (Ref: post #7 above). I guess 'opinions' do vary on this.

Quote: All my HDS lights have the UC glass. Henry as well. The sapphire is more scratch resistant, but also a little more brittle. Sapphire will cut a few lumens, but not anything even worth being concerned about.

Quote Source:
 
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