I noticed recently that if I held my best (finest) finishers up to a light source, along the longest axis and tilted just a degree or two from the parallel line of sight, that there was a correlation between the sharpness of the image and the finishing quality given by that stone.

For example, I have have six cotis, some better finishers than others. The best finishers reflect the light source almost as a mirror would. The better cutters, or pre-finishers, give a cloudier reflection. The differences are subtle, about on a par with various HHT outcomes, and I suspect each individual would have to establish his own standards.

I've also tried this with my manmade stones. The 8K Norton gives a pretty accurate reflection -- though not as precise as my Eschers, Nakayamas, or even my Guangxi. The 4K stone shows a light source, but a very muddled one.

Could some of you try this and report back? It might be useful as a quick indicator of the finishing qualities of an unknown stone. I realize nothing will ever substitute for the actual honing experience, just as nothing will ever substitute for the shave test on a blade.

Or maybe it's just my fevered imagination.