A+ Grade Herkimer Diamond earrings. The Herkimer Diamonds are prong set and measure 7-8mm x 4-5mm. The prongs and post are sterling silver with a touch of rhodium which helps prevent tarnish. Herkimer Diamonds are quartz formations which because of their brilliance and diamond shape have been given the name. Mined only in Herkimer, NY. Herkimer diamonds help release energy blockages and also help enhance dream recall. Really nice. You will receive these in a black cotton lined box, all ready for gift giving.