Ceylonite and pleonaste are names used for black spinel. These names are also used for gray and blue spinels that are so dark that they appear to be black (unless they are examined with a bright light). Although these dark spinels are not commonly seen in jewelry, they are exceptionally durable because of their hardness.…

Spinel is frequently faceted into round and cushion cut (square with rounded corners) gems. These faceted shapes can be efficiently cut from octahedral spinel crystals with a minimal amount of lost weight.

Like diamond, spinel often crystallizes in perfect octahedral crystals. An octahedron is a three-dimensional shape that resembles two four-sided pyramids attached at their bases. Octahedral crystals of spinel are often mined from marble, but they are more often found as water-worn crystals in stream sediments. Especially nice crystals are highly prized by mineral collectors or…

The word “phenomenal” has a special use in gemology. The name is used for gems that have a special optical reaction to light. Some specimens of spinel contain a network of thousands of needle-shaped crystals of rutile that reflect light from specific directions. In some specimens of spinel, these reflections produce a six-ray star when the gem…

Spinel is many times rarer than ruby, has comparable color, luster, and a wonderful appearance – but it sells for a fraction of the price. Why is that? An important reason is that jewelry manufacturers and jewelry buyers are still not thinking about spinel – and that makes spinel a gem that does not have…

The two most popular focal stone colors in jewelry are red and blue. Spinel occurs in red and blue hues that rival those of the finest rubies and sapphires. In fact, it was not until the mid-1800s that European scientists and gem dealers learned that spinel and ruby were two different minerals. Before then, several…

During the Middle Ages, many rulers of countries in Asia and Europe had their names inscribed on significant gems in their royal collections. Many of these stones survive uncut today, preserving the histories inscribed on their surface.

One of the most important things that can influence the popularity of a gem is to be named as a birthstone. That happened for spinel in July 2016, when the American Gem Trade Association and the Jewelers of America named it a birthstone for the month of August. Spinel was unknown to most people when…

Toughness is the ability of a material to resist breaking. Spinel is very tough. It does not exhibit cleavage (planes in its crystal structure that are prone to separation) like diamond and topaz. It is not as brittle or prone to fractures as emerald, topaz, and many other hard gems. Spinel is one of the…

Spinel is one of the hardest gems. Hardness is the resistance of a material to being scratched. A high hardness helps a gem resist abrasion without scratching. This is a very important property for gems that will be worn for years – or for a lifetime. Today an increasing number of couples are selecting colored stones for…