Each piece is truly one of a kind as each natural Herkimer diamond has its own unique color, texture, and beauty. This handmade ring features one Herkimer Diamond and a tiny genuine diamond bezel set on one side. 18kt yellow gold vermeil Herkimer Diamond Size: Adjustable sizes 5-8 handmade in Brooklyn NY by Felix Z What is a Herkimer Diamond? Herkimer diamonds are not actually diamonds at all. They are a form of double-terminated quartz crystals that began forming 500 million years ago in the dolomite outcrops throughout Herkimer County, New York and the Mohawk River Valley.