Sphene, also known by its mineral name titanite, is a rare gemstone composed of calcium, titanium, and silicate. In some specimens, additional elements such as aluminum, chromium, manganese, and iron may be present. It can even contain rare earth elements like niobium, cerium, and yttrium, which make each stone unique. Because of its complex composition, sphene is highly valued by collectors. Although beautiful, it remains lesser-known compared to more common gemstones.