I got the color checker yesterday. I don't know if the colored squares are on cardboard or not but the squares are captive in a thin black frame which is solid black on the back side. The assembly looks pretty nice to me and the flat, non reflective surfaces of the colored squares is also very nice! I believe all things considered, the price was worth it. I have taken a couple pictures but before I post anything, i want to play with these some more and get a better feel for what might be worthy of posting beyond just a picture of the color checker!
There is a small guide pamphlet that comes with the checker and it alone has a bunch of information including the RGB constituents for each square so in PhotoShop, for instance, you could likely duplicate these colors. I don't think these are going to turn out to be tight and band specific but won't have a feel for this until I sample them with the spectrometer which I will do later on when I get a chance.
There is mention of some squares that will change if your light source has problems and this supports the fact that these squares are not a single band. The squares are named and in the naming itself, I think I see a problem for me!! There is a "blue flower" which doesn't jibe with my perception. The blue flower looks more like a lavender or blue/purple to me. I will be curious if younger eyes see this color with the blue in it's namesake?!?! If yes, this may point to the yellow tint of my eyes and why I prefer more blue in my light to overcome the yellow?!?!
Here is the ColorChecker under bright direct sunlight. In fact it was so hot and the deck was so hot that the Color Checker started to curl up like a potato chip and I took it out of the sun quickly!
The squares are numbered from left to right, top row and then next row and then next row. The Blue Flower is #5. #1 is titled dark skin and #2 is called light skin. The notes say that #13 which is blue will turn purple easily if there is too much red in the lighting.
My guess at the best means of comparing this checker under different lights would be to get the camera exposure off one of the gray squares for the various shots to insure a similar saturation from shot to shot. You photo experts may have a better idea.