Blue & Black Carbon Fiber Tungsten Carbide Men's /Women's Wedding Ring Band 8mm (12.5) Tungsten Carbide is the only rare and exotic metal that has a permanent polish and finish that will endure until the end of time. The heavy weight and the enduring finish of a tungsten carbide ring, speak of commitment, security and an everlasting bond. Tungsten Rings are the most wear-resistant rings available on the planet.