Mg(Al2O₄)
magnesium aluminum oxide

For many centuries, most gem spinels were misidentified as sapphires or rubies because they have similar properties and occur in the same geological deposits. The two inch faceted "ruby" in the center of the British Imperial Crown was only recently identified as a spinel! Spinels also occur in a vast array of colors. They are slightly softer than sapphires but still very durable. The earliest spinels, used as ornaments were found in Buddhist tombs in Afghanistan. Blue spinels have been found in England, dating back to the Roman occupation (51 BC to 400 AD).

Spinel is a favorite of gem dealers and gem collectors due to its brilliance, hardness and wide range of spectacular colors. In addition to beautiful rich reds, spinel can be found in a range of pastel shades including a spectacular vibrant hot pink with a trace amount of orange, mined in Myanmar. Spinel also comes in beautiful blues which are sometimes called cobalt spinel, but these are very very rare.