August boasts not one, but three recognized birthstones: peridot, sardonyx, and spinel. While historically peridot and sardonyx held prominence, spinel was added to the list more recently, offering a diverse range of options for those born in the eighth month. These gemstones, though differing in composition and appearance, share a rich history and enduring symbolism. This article will explore the origins, properties, historical significance, and lore surrounding each of these August birthstones.
A Historical Overview
The tradition of associating gemstones with specific months dates back to the twelve stones in the breastplate of the High Priest Aaron, representing the twelve tribes of Israel. However, modern birthstone lists have evolved since 1912, with various organizations updating the roster to include a wider selection of gems. Peridot and sardonyx have long been recognized as August birthstones, steeped in ancient traditions, while spinel’s inclusion is a more recent development. These stones, despite not always achieving the same popularity as diamonds, emeralds, or rubies, possess unique qualities that make them delightful additions to any jewelry collection.
Peridot: The Gem of the Sun
Peridot, a member of the olivine mineral group, is renowned for its distinctive olive-green hue. Its color, ranging from yellowish-green to brownish-green, is determined by its iron content. Remarkably, peridot maintains its color consistently across different lighting conditions, a rare trait among colored gemstones. Ancient Romans aptly named it the “evening emerald” due to its ability to remain visible even at night. Egyptians referred to it as the “gem of the sun,” and some historians theorize that Cleopatra’s famed emerald collection largely consisted of peridot.
Historically, peridot has often been mistaken for emeralds, a testament to its vibrant green color. The gemstone’s properties include a refractive index between 1.65 and 1.69, a birefringence of 0.035 to 0.038, a specific gravity of 3.34, and a Mohs hardness ranging from 6.5 to 7. This hardness makes it suitable for most jewelry applications, though care should be taken to avoid significant scratches.
Peridot has been sourced from various locations throughout history, initially from ancient Egypt around 2000 BC. Subsequent discoveries have yielded high-quality peridot in Burma, America, Brazil, Mexico, Pakistan, and China. Uniquely, peridot has even been found within pallasite meteorites, estimated to be between 4 and 5 billion years old, offering a glimpse into the origins of our solar system. In 2005, peridot was discovered in comet dust returned by the Stardust robotic space probe, further cementing its extraterrestrial connection. The presence of peridot in these celestial bodies provides clues about the formation of our solar system.
Peridot is associated with prosperity, growth, openness, and strengthening life. It is also the traditional gift for a 15th wedding anniversary. Notable examples of peridot in historical artifacts include the 200-carat gemstones adorning the shrine of the Three Holy Kings in Germany’s Cologne Cathedral, previously misidentified as emeralds.
Sardonyx: Bands of History
Sardonyx is a captivating combination of two types of chalcedony: sard and onyx. It features alternating bands of brownish-red to brown to dark orange sard and typically white or black layers of onyx. This banded appearance has made it a popular material for carving cameos and intaglios for millennia. In ancient times, sardonyx was favored by Romans for creating seals and signet rings, as hot wax would not adhere to its surface.
Sardonyx is sourced from India, but can also be found in Brazil, Uruguay, the United States, and Germany. The reddish-brown color of sardonyx is believed to embody both comfort and power. While its crystal structure differs from the more crystalline appearance of peridot, it possesses a unique earthy and rustic aesthetic.
Spinel: A Ruby Imposter Revealed
Spinel, derived from the Latin word spina meaning thorn, referencing the shape of its crystals, presents a wealth of colors including intense red, vibrant pink, orange, purple, violet, blue, and bluish-green. For centuries, spinel was often misidentified as ruby, with some of history’s most famous “rubies” actually being spinel. A prime example is the approximately 170-carat Black Prince’s “ruby,” owned by Moorish and Spanish kings before being gifted to Edward, Prince of Wales, in 1367. It wasn’t until the 18th century that spinel was definitively distinguished from ruby based on their chemical differences. Today, this historic red spinel is prominently set in Great Britain’s Imperial State Crown, positioned above the Cullinan II diamond.
Red spinel, along with other red gems, was historically believed to be a remedy for blood loss and inflammatory diseases, and to promote harmony and ease anger. It is traditionally given as a gift for a 22nd wedding anniversary.
Major sources of spinel today include Tajikistan, Myanmar, Sri Lanka, Vietnam, Tanzania, and Pakistan. Spinel deposits in Tanzania, discovered in 2007, have yielded captivating pinkish and orangy-red spinel, while other Tanzanian mines produce purple and blue hues. Spinel registers an 8 on the Mohs scale of hardness, making it a durable gem suitable for rings and other jewelry. It can be safely cleaned using ultrasonic and steam cleaners, though caution should be exercised if fractures are present, in which case warm soapy water is recommended. Spinel is stable when exposed to light and chemicals, but high heat can cause some colors to fade.
Gemological Properties Comparison
The following table summarizes the key gemological properties of the three August birthstones:
| Gemstone | Mineral | Color | Refractive Index | Mohs Hardness | Specific Gravity |
|---|---|---|---|---|---|
| Peridot | Olivine | Yellowish-Green to Olive | 1.65 - 1.69 | 6.5 - 7 | 3.34 |
| Sardonyx | Chalcedony | Banded Red/Brown & White | N/A | 6.5 - 7 | 2.64 - 2.91 |
| Spinel | Magnesium Aluminate | Red, Pink, Blue, etc. | N/A | 8 | 3.58 - 4.00 |
Jewelry and Care
Both peridot and sardonyx are versatile gemstones for jewelry, though they offer distinct aesthetics. Peridot’s crystalline appearance lends itself to more elegant designs, while sardonyx’s matte finish provides an earthy, rustic vibe. These stones can be beautifully complemented by other gems, such as diamonds and tanzanite, particularly when paired with peridot.
As noted, peridot’s hardness of 6.5-7 on the Mohs scale requires careful handling to avoid scratches. Spinel, with a hardness of 8, is more durable and suitable for everyday wear. Sardonyx, also with a hardness of 6.5-7, benefits from gentle cleaning and protection from harsh impacts. All three gemstones can be cleaned with warm, soapy water and a soft cloth.
Conclusion
Peridot, sardonyx, and spinel represent a diverse and historically rich selection of August birthstones. From the “gem of the sun” found in meteorites to the ancient Roman seals carved from sardonyx and the historically misidentified “rubies” that are actually spinel, each gemstone carries a unique story and symbolism. While they may not always be as widely recognized as other birthstones, their beauty, durability, and fascinating histories make them treasured additions to any gemstone collection.