I don’t think so. I’ve been playing with the same granite tile for a project I’m working on. It ablates the rock. More power, more gray color and it washes over so a low power engrave shows a lot of unmolested granite but more power with the same DPI & GF LPI shows more gray/whiteish to a point. A low power etch may show a lot of untouched granite color and a high one a lot. A box may only show a little or even no white when engraved with low power but once you get to a rather low power setting (a 50¢ piece for example ) and the whole box will be white.
I’ve been playing with a photo trying to get it to engrave. When it finally hits the GF it’s b&w so it’s either burning or not. A grayscale though shows the same effect.
I think it’s engraving like ceramic tiles or marble. There’s material ablation occurring which is different than glass (although I don’t have a way to do microscopic evaluation). My 12x12 tile has about 20 tests on it with different settings. (A 2x3 photo)