4MM Gold Color Tungsten Carbide Band Ring Women Wedding Engagement Zircon Jewelry Alliance Jewelry Size 4-8 TU046R wear-resistant rings available on the planet. Tungsten is about 10 times harder than 18K Gold, 5 times harder than tool steel, and 4 times harder than titanium. Tungsten measures between 8 and 9 on the Mohs hardness scale. (Diamonds are a 10 - the highest.) Due to their extreme hardness, Tungsten Rings will hold their shape and shine longer than any ring on the market. Tungsten rings have been referred to as "Permanently Polished Rings."Our Tungsten Forever rings are cobalt-free and hypoallergenic.