Zirconium is a light and extremely durable metal similar to titanium. One benefit of zirconium is that when heat treated, the surface becomes black and attains a sapphire hardness. The ring in questions has two raised lines of natural zirconium which contrast beautifully with the rich black. Other widths and depths are available and also in a satin finish – the ring imaged is 7mm width by 2.25mm depth. Please call or email for more details.