Barrel shaped black and white semi precious gemstone Tuxedo Agate Designer cabochon 51 mm by 18 mm and 4.5 mm thick.
This is actually semi precious gemstone Brazilian Agate that has been dyed a rich black!
The natural white lines come through and make a beautiful specialty designer cabochon known as Tuxedo Agate.
Agate is a form of Chalcedony, or a microcrystalline quartz. It forms in concentric layers in a wide variety of colors and textures. It has a hardness of 7 and wears great in jewelry.