Art Deco Style Round Black Onyx Cabochon & Marcasite Halo Ring in 925 Sterling SilverA stunning Art Deco style ring crafted from sterling silver set with a central round black onyx cabochon stone, surrounded by sparkling marcasite gemstones. This traditionally banded gemstone is a member of the chalcedony family and has been used in jewellery for centuries, most notably black onyx in ancient cameo jewellery. Once used as a substitute for the shine of a diamond, the natural semi precious gemstone marcasite is now celebrated for its