Edge Tester

I ran across this knife sharpness tester while surfin' the net:

http://www.razoredgesystems.com/prod...&category_id=8

Would it be useful as a test for razor sharpness?

That is really similar to the barrel of a white Bic pen. It is since standard, but so is your thumb nail.

I'd suggest this would only be marginally useful for testing if a bevel is fully set...not nearly sensitive enough to gauge razor sharpness IMO.

Like the thumbnail test, it would probably take the shaving edge off a razor and return it to just before the bevel is properly set.

In my short experience an illuminated pocket microscope 60x-100x, I have one similar to this one, is critical for me to get a good edge higher than 1000 grit. It can also be used to visually check an edge with out a high probability of setting the edge back a level in the honing process, like the thumb nail test can at high grits. For me the HHT is basically useless, since my hair is not suitable for that test.
Take a look in the wiki for a good overview of tests suitable for razors, but the shave test is THE essential test.

What Datsots said...and I'll add that I also use the same magnifier, recommended to me by Howard of The Perfect Edge.
Once you get a bevel set, and begin to actually hone an edge, the magnifier really shows you what you're accomplishing, (or not!). When you go to 8K and up, to polish that keen edge, you can really see how it's coming and when the cutting edge gets a mirror finish on the bevel.

Once you've got it to where you think it needs to be, a little water on your arm hair and a gentle swipe will tell you if you're cutting well enough to shave. You can join the ranks of honers with moth-eaten looking forearms and a BBS face!