Semi precious cabochon stone. Ryolite cabochon stones, flat back, measuring 18mm. Ryolite is a very pleasing stone with a lot of detail and marking. An olive green which can have a various color combination of markings (including coral, tan, white, gray etc.) and a bit of ochre swirling. We cull our stones for quality to make sure of no cracks or chips and that the over-all appearance of the stone is very pleasing. You should expect variations in all natural, semi precious stones. Looks great in any of our mounts and I love it in the new pewter findings from B'sue by 1928. No two are exactly alike. Sold by the piece.