Today I tried some (red-dyed) Howlite. It’s a naturally white stone with grey veins and is usually dyed other colors (e.g., turquoise-colored to make “turquenite”).
Whereas the agate I experimented with before turns a bright white when cut, the Howlite reveals its natural mottled white/grey interior. So scoring doesn’t stand out as much and engraving yields inconsistent brightness. Not all designs are going to look great on this stone, but it will certainly have its uses.
The first photo is an engrave. The second is a cut (score). Unlike my agate test I used the front/back of a single bead in this test. It’s an opaque stone, so there was no reason to waste two separate pieces on a test.
This particular piece started out with a lot of grey veins. I have other pieces that look like they’re probably a more solid white under the red dye, so they may produce better results on a busy pattern like this. The veiny ones are probably better used for simpler designs.
The stone is very soft and cuts go quite deep. The start/stop points for cuts are quite obvious (and I imagine could be even more distracting on an angular design) but that may perhaps improve as Glowforge improves the software. I doubt I’ll do any more cuts on this stone, however. I think it looks a lot better when engraved.
There’s a lot of black soot produced on both cuts and engraves, with a noticeable (but not strong) smell afterwards. It washes off easily enough. (These photos are post-washing.)