Loose Diamonds, Bridal Jewelry, Findings, Mill Products, Custom Casting, Refining - Hoover and Strong eco jewelry, bridal jewelry, jewelry findings, mill products, refining, diamonds, gems, finished jewelry, custom casting, Harmony Metals and Gems, earth-friendly metals, green, recycled precious metals Hoover and Strong is an eco-friendly refiner and manufacturer of precious metals. We offer many products and services that fall under our Harmony brand, including loose diamonds, bridal jewelry, findings, mill products, custom casting and refining.