Early coin inlay chips from Bud Jones had black marking in the incuse lettering. Presumably, this was to make the lettering more readable. With lots of play, the black started to flake off. Some collectors even cleaned the coins to get rid of the "dirt" on the chip. Here's an example of a Desert Inn chip that has most of the black lettering intact.

I collect these black-lettered chips but they are pretty difficult to find in original condition. Most were made in the early 1970s. I'd really like to learn how they were manufactured. They are not "hand painted" as the bottom of the letters is all that is black. Since the metal centers were "coined", is it possible they were struck in a press with coated film in between, something like hot-stamping? I doubt it, but can't think of any other process that might have been used.