For centuries, one of the world's most dazzling gemstones lived in disguise. Mistaken for ruby and featured in some of the most famous crown jewels, spinel earned its nickname as “the great impostor” of gemstone history. But in 2016, this radiant gem stepped out of ruby’s shadow to become an official birthstone for the month of August, joining the yellow-green peridot and zebra-striped sardonyx.
Spinel’s rise to official birthstone status was a rare event. Since the modern birthstone list was first established in 1912 by the American National Retail Jewelers Association (now Jewelers of America), the list had only been amended a few times. So when the American Gem Trade Association (AGTA) and Jewelers of America announced spinel’s inclusion, it was met with excitement — and some surprise — throughout the jewelry world.
Long prized for its vibrant red hues, spinel was often indistinguishable from ruby until the late 18th century. The two share similar colors, due to the presence of chromium in their chemical makeup. However, spinel is composed of magnesium aluminum oxide, while ruby is a variety of corundum made from aluminum oxide. It wasn’t until 1783 that mineralogists formally recognized spinel as a mineral distinct from corundum.
By then, many legendary “rubies” had already found their way into royal collections. Among the most famous are the 170-carat Black Prince’s Ruby in the British Imperial State Crown, the 361-carat Timur Ruby presented to Queen Victoria in 1851, and the 398-carat gem atop the Imperial Crown of Russia. Each was later confirmed to be a red spinel.
While spinel is best known in rich reds, this versatile gem occurs in a rainbow of colors, from soft pinks and purples to fiery oranges and steely blues. In its purest form, spinel is colorless, but trace elements give rise to its kaleidoscopic variety. Blue spinels are colored by iron and cobalt, while vibrant reds are chromium-rich.
Spinel’s durability also makes it a standout gemstone for jewelry. Ranking 8.0 on the Mohs hardness scale, it is a resilient choice for everyday wear. Ruby, by comparison, rates a 9 on the hardness scale.
Today, spinel is mined in locations around the world, including Myanmar, Sri Lanka, Vietnam, Tanzania, Tajikistan and Afghanistan. Myanmar (formerly Burma) is known for producing some of the finest pink and red spinels on the market.
Once an overlooked understudy to ruby, spinel is now getting its well-deserved moment in the spotlight — especially for those celebrating August birthdays with a gem as bold and colorful as they are.
Credits: 40.25-carat Tajikistan spinel photo by Greg Polley/Smithsonian. British Imperial State Crown by Cyril James Humphries Davenport, Public domain, via Wikimedia Commons. Spinel crystals by Rob Lavinsky, iRocks.com – CC-BY-SA-3.0, CC BY-SA 3.0, via Wikimedia Commons.
