Named for the Greek word for “wedge” due to its distinctively shaped crystals, sphene—known mineralogically as titanite—is a rare, exotic gemstone beloved by collectors for its incredible optical pyrotechnics. It possesses an exceptionally high dispersion rate that comfortably exceeds that of a diamond, allowing it to split light into blazing, intense flashes of spectral color and rainbow fire. Typically found in an earthy yet vibrant palette of chartreuse greens, rich honey yellows, and warm golden-browns, sphene also boasts a high refractive index and a brilliant adamantine (diamond-like) luster. Alongside its mesmerizing fire, the gem is strongly double refractive, causing light traveling through it to split into two rays; this creates a unique visual doubling of the pavilion facets, giving the stone a lush, velvety depth. Because it is quite soft and brittle, measuring a modest 5 to 5.5 on the Mohs scale, sphene requires highly skilled cutting and careful setting, making a finely faceted specimen a prized and delicate treasure for elite jewelry connoisseurs.