Sphalerite, also known as blended, is an important ore of zinc. It is usually very dark brown to black in color, but, occasionally, transparent yellowish brown or green stones are found that can be faceted. Since sphalerite is soft and has perfect cleavage, it is not suitable for jewellery, and is faceted for museums and collectors only.

Spinel occurs in granites and metamorphic rocks, and is often found in association with corundum. Octahedral crystals and water worn pebbles in a wide range of colors are found in the gem gravels of Burma. Sri Lanka and Madagascar. Other localities include Afghanistan, Pakistan. Brazil. Australia. Sweden. Italy. Turkey the former USSR, and the USA.

Synthetic spinal has been manufactured since 1910. It has been used to imitate diamond, or colored to imitate stones such as aqua marine and zircon. Blue synthetic spinel, colored by cobalt, has been used to imitate sapphire. The name may derive from the Latin word spina, meaning little thorn, referring to the sharp points on some crystals.