18KTGP Black Onyx Round Stone Set In A Solitaire Crown Surrounded By Austrian Crystals. Black Onyx is the anniversary gemstone for the 10th year of marriage. Onyx is a variety of the microcrystalline quartz, called chalcedony. Genuine Natural High Quality Ring With Semi-Precious Stones. The Ring Has Hand Prong Settings & Were Classis Vintage & Crafted Finishes Nickel Allergy Free, Base Metal- Brass, 18KTGP Yellow Gold Electroplate Finish. The Ring Has 120 Mils 18kt Gold Finish , Signed D.O. 18KTGE. With Swarovski Crystals. Available in Size 6. View Photos for Further Details.