Those copper tone finishes are meant to be engraved, but I didn't use it as an external face. I used it facing up to provide a bit of color around the edges to see when you're looking down at the board. I don't know how engraving works on the black side. I suppose it would still work...
For some reason I thought the copper color was part of the protective mask.

So Glissant, it will have a copper colored background, and don't invert the colors.

And, because of the USB cutout, you'll never see the engraving, which will be under your PCB.
