I wish I hadn't lost my precious hand lens. It was as good or better than my eyes at determining how sharp a hook was. Sometimes I'd look at a "sharp" hook and be amazed at how dull it actually was. When I sharpened such hooks with a file, boy were they sharp. All I gotta say is, get a hold of a magnifying glass and be amazed.

By the way, I don't recommend using the fingernail test. Just don't see the need to ruin the nice sharpening job you did on the hook, esp when sharpening finer wire hooks.

I usually just use a Luhr-Jensen flat file for most hooks and a hook honing stone for either detail work, touch ups or small/fine wire hooks .