I don't think you've been in the hobby long enough to remember the late Jeff Laudeman (RIP "Diceman" ). Jeff wrote the original dice guides, and set a lot of the standards for dice collectors. One thing that he used to do....if the hot stamp was totally gone from old dice, he used a white crayon to color over/fill in the stamp. Then use a paper towel to wipe off the excess crayon. Of course if you're going to sell the dice, I'd advise against doing that...or at least tell prospective buyers that the hot stamp has been enhanced. If I remember right, a quick swipe with some Goo Gone will remove the crayon entirely.