After another light cleaning and inspection without the loupe, I found what appears to be "Ideal ....". Sort of a script font. Can't make out the second word, but it could start with "F", or "P" or possibly an "R". I originally mistook the lettering for just random marks from wear/abuse. Plus, I think I was too close to my work with the loupe. :-[
I never considered a sugar rasp, but I can see where that's entirely possible. But I don't think the "diamonds" are sharp enough for a fish scaler, although the edges certainly were before someone hacked them on something ... like a skillet. ::)
