The month of August is uniquely distinguished in the world of gemology by possessing three official birthstones: Peridot, Spinel, and Sardonyx. While Peridot often claims the spotlight with its vivid lime-green hue, the history of August’s birthstones is a complex tapestry woven from ancient tradition and modern adaptation. Sardonyx stands as the original and most traditional birthstone for the month, with a history spanning over four millennia. Peridot became the official modern birthstone in 1912, valued for its distinct color and formation under extreme geological conditions. Most recently, in 2016, Spinel was added to the list by the American Gem Trade Association (AGTA) and Jewelers of America (JA), offering consumers a wider spectrum of color and an alternative to the ruby.
These three gemstones offer a diverse palette, ranging from the olive greens of Peridot to the banded reds and whites of Sardonyx, and the vibrant reds, pinks, and blues of Spinel. This article provides a detailed examination of each stone, exploring their geological origins, historical significance, gemological properties, and the metaphysical beliefs associated with them.
The History and Lore of August’s Gems
The journey of these three stones through history reveals a narrative of confusion, rediscovery, and evolving cultural value.
Peridot: The Gem of the Sun
Peridot holds a storied past, often intertwined with other green gemstones due to its similar appearance. The ancient Egyptians held this gem in high regard, mining it on the Red Sea island of Topazios—a location that ironically contributed to the confusion with topaz. They referred to Peridot as the “gem of the sun,” believing it offered protection against terrors of the night and bad dreams. Its allure was such that it was frequently mistaken for emeralds throughout history.
Evidence of this confusion is found in significant historical artifacts. The Shrine of the Three Holy Kings in Germany’s Cologne Cathedral is decorated with 200 carats of gems originally believed to be emeralds but later identified as Peridot. Some historians even speculate that Cleopatra’s famous collection of emeralds may have actually consisted of Peridot. The name "Peridot" is derived from the Arabic word "faridat," meaning gem.
Sardonyx: The Original August Stone
Sardonyx is the earliest of the three birthstones, with a history dating back more than 4,000 years. As a variety of banded Chalcedony, a member of the Quartz family, it has been used since ancient times for cameos and intaglios. Its durability and striking banding made it a favorite of ancient Roman and Greek artisans. Historically, Sardonyx was believed to bring courage and protection, particularly to warriors.
Spinel: The Great Impostor
Spinel’s history is defined by its remarkable resemblance to ruby. For centuries, the finest red spinels were mistaken for rubies, earning them the name "Balas Ruby." The most famous example of this case of mistaken identity is the "Black Prince's Ruby," a massive 170-carat red stone that adorns the British Imperial State Crown. It was not until the late 18th century that Spinel was recognized as a distinct mineral species. Its recent addition to the August birthstone list in 2016 acknowledges its beauty and corrects its historical overshadowing by the ruby.
Geological Formation and Sources
The geological origins of these three gems are as distinct as their appearances.
Peridot: From the Mantle to Meteorites
Peridot is the gem-quality variety of the mineral olivine. Its formation is unique among gemstones; it is created under extreme conditions. Peridot can be found in hardened lava that carries it from deep within the Earth’s mantle, bringing it to the surface. It is also one of the few gemstones found in meteorites that have traveled from outer space. Its distinct lime-green color is attributed to the presence of iron within its chemical structure. Unlike many other gemstones, Peridot occurs in only one color, though the shade can vary from yellowish-green to olive to brownish-green depending on the iron content.
Spinel: The Magnesium Aluminum Oxide
Spinel is a magnesium aluminum oxide (MgAl₂O₄). While it forms under similar conditions as ruby, it is chemically distinct. The red varieties of Spinel are colored by chromium, similar to ruby, but the absence of iron in its composition gives it a vibrancy that is highly prized. Historically, the finest spinels came from the Badakhshan region of Central Asia (specifically the valley of the river Kafirnihan), but sources are also found in Sri Lanka, Thailand, and Vietnam.
Sardonyx: A Variety of Quartz
Sardonyx is a banded variety of Chalcedony, which is a cryptocrystalline form of Silicon Dioxide (SiO₂). It consists of alternating layers of sard (a reddish-brown chalcedony) and onyx (a white or black chalcedony). This banding is the result of silica deposition in volcanic rock fissures. Sardonyx is found in various locations worldwide, including India, Germany, the Czech Republic, and the United States.
Gemological Properties
Understanding the physical and chemical properties of these gems is essential for identification, valuation, and care.
Peridot
Peridot is a relatively hard gemstone, making it suitable for various types of jewelry. However, it does possess some cleavage, meaning it can be chipped if struck against a hard surface.
- Chemical Composition: (Mg, Fe)₂SiO₄
- Hardness (Mohs Scale): 6.5 – 7
- Crystal System: Orthorhombic
- Refractive Index: 1.65 – 1.69
- Color: Yellowish-green to greenish-yellow (due to iron content).
Spinel
Spinel is prized for its excellent hardness and lack of cleavage, making it durable for daily wear. It often possesses a high refractive index, giving it a lively brilliance.
- Chemical Composition: MgAl₂O₄
- Hardness (Mohs Scale): 8
- Crystal System: Cubic
- Refractive Index: 1.71 – 1.73
- Color: Wide range, including vivid red, pink, orange, cobalt blue, and black. The red variety is the most popular.
Sardonyx
As a variety of quartz, Sardonyx is very durable and resistant to chemical wear. Its hardness makes it excellent for carved items like cameos.
- Chemical Composition: SiO₂ (Silicon Dioxide)
- Hardness (Mohs Scale): 7
- Crystal System: Trigonal (Microcrystalline)
- Refractive Index: 1.53 – 1.54
- Color: Banded layers of reddish-brown (sard) and white or black (onyx).
| Property | Peridot | Spinel | Sardonyx |
|---|---|---|---|
| Mineral | Olivine | Spinel | Chalcedony (Quartz) |
| Chemical Formula | (Mg, Fe)₂SiO₄ | MgAl₂O₄ | SiO₂ |
| Mohs Hardness | 6.5 - 7 | 8 | 7 |
| Color Range | Shades of Green | Red, Pink, Blue, Black | Banded Red/Brown & White |
| Crystal System | Orthorhombic | Cubic | Trigonal (Micro) |
Symbolism and Metaphysical Beliefs
Across cultures and centuries, these gemstones have been attributed with various powers and meanings.
Peridot: Emotional Balance and Light
Peridot is frequently associated with light, positivity, and growth. Its connection to the heart chakra in crystal healing practices suggests it promotes love, compassion, and emotional balance. As the "gem of the sun," it is believed to bring warmth and good fortune. In modern metaphysical beliefs, Peridot is thought to dispel negative emotions and foster a sense of renewal and strength.
Spinel: Vitality and Renewal
Spinel is often associated with revitalizing energy. Red spinel, in particular, is linked to passion and physical energy. It is believed to help overcome lethargy and provide a boost to one’s vitality. The stone is also historically associated with hope and joy, serving as a reminder of one's inner strength.
Sardonyx: Courage and Protection
Historically, Sardonyx was a stone of warriors and orators. It was believed to impart courage, steadfastness, and stamina. In ancient Rome, it was worn as an amulet for protection during battle. In spiritual traditions, Sardonyx is thought to promote discipline and logical thinking, helping the wearer maintain composure under pressure.
Care and Cleaning
Proper maintenance is crucial to preserving the beauty of these gemstones, and their care requirements differ based on their physical properties.
Peridot Due to its hardness of 6.5 to 7 and the presence of cleavage, Peridot requires careful handling. It is susceptible to chipping and scratching if knocked against hard surfaces. Cleaning should be done with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaners, as the heat and vibrations can cause damage. Sudden temperature changes should also be avoided.
Spinel Spinel is relatively hardy, with a Mohs hardness of 8 and no cleavage. It is durable enough for everyday wear. It can be safely cleaned using warm soapy water and a soft brush. Ultrasonic cleaners are generally safe, but it is best to avoid extreme temperature changes.
Sardonyx As a member of the quartz family, Sardonyx is quite durable with a hardness of 7 and no cleavage. It is resistant to most chemicals. Cleaning is simple: use warm, soapy water and a soft cloth or brush. It can also be cleaned safely in an ultrasonic cleaner.
Conclusion
The August birthstones—Peridot, Spinel, and Sardonyx—offer a remarkable diversity in color, history, and meaning. From the ancient protective powers of Sardonyx to the solar brilliance of Peridot and the rediscovered allure of Spinel, these gems provide a rich selection for those born in the eighth month. Whether one is drawn to the scientific intrigue of Peridot’s extraterrestrial origins, the durability and vibrant hues of Spinel, or the ancient, banded charm of Sardonyx, each stone carries a legacy of geological wonder and human admiration. Their varied properties and care requirements underscore the unique nature of each gem, ensuring that there is a perfect August birthstone for every individual and occasion.