This is a 18k yellow gold 10mm Crownwork® bezel set green citrine ring on inverted shank. All of the gold we use is certified eco-responsible, recycled metal. Unlike mining, where approximately 20 tons of waste is generated to produce just one ounce of gold, refining precious metals has virtually no waste and is much better for the earth. Citrine is the yellow to red-orange variety of crystalline quartz.