August is a unique month in the gemological calendar, distinguished by not one, but three distinct birthstones: Peridot, Spinel, and Sardonyx. This triad offers a remarkable spectrum of color, history, and symbolism, ranging from the vivid lime greens of a volcanic gem to the fiery reds of a stone once mistaken for ruby, and the ancient, banded layers of sardonyx. While Peridot has emerged as the most recognized modern choice, Spinel and Sardonyx possess deep historical roots and unique properties that make them equally compelling. Together, they represent a diverse palette of options for jewelry lovers and those seeking meaningful adornments for August birthdays.
The evolution of August's birthstone list is a testament to the changing dynamics of the jewelry industry and the discovery of new sources. Sardonyx, a form of onyx, stands as the original historical birthstone, with a legacy stretching back thousands of years. Peridot, the "gem of the sun," was added later, celebrated for its singular color and extraterrestrial origins. Spinel, the most recent addition officially recognized in 2016, was long undervalued, often serving as an imposter for ruby in royal collections. This article delves into the geological origins, gemological properties, historical lore, and practical care for each of these captivating August stones.
Peridot: The Gem of the Sun
Peridot is perhaps the most celebrated of the August birthstones, known for its distinctive and consistent hue. As the gem variety of the mineral olivine, its chemical composition is (Mg,Fe)₂SiO₄. Unlike many other gemstones, peridot does not require heat treatment to enhance its color; its signature yellowish-green to greenish-yellow appearance is natural. This color is derived from its iron content, with higher iron levels resulting in a more intense green.
Geological Formation and Sources
Peridot’s origin story is one of the most fascinating in the gem world. It is formed under extreme conditions deep within the Earth’s mantle and can be brought to the surface through volcanic activity. Notably, peridot has also been found in pallasite meteorites, remnants of protoplanets that offer a glimpse into the formation of our solar system. This extraterrestrial connection reinforces its ancient moniker, the "gem of the sun."
Historically, the most significant source of peridot was the island of Zabargad (also known as Topazios) in the Red Sea. Ancient Egyptians mined this island for centuries, and the peridot extracted there was so adored that it was believed to ward off "terrors of the night." The gems from Zabargad were often confused with emeralds, a misidentification that has led to speculation that Cleopatra’s famous emerald collection may have actually been peridot. This confusion is understandable; the Shrine of the Three Holy Kings in Germany’s Cologne Cathedral is decorated with 200 carats of gems long believed to be emeralds, which were later identified as peridot from Zabargad. Other notable sources include Pakistan, Myanmar, and the United States (Arizona).
Gemological Properties
Peridot is a relatively hard stone, making it suitable for various types of jewelry. Its key properties are as follows:
- Hardness: 6.5 to 7 on the Mohs scale.
- Crystal System: Orthorhombic.
- Refractive Index: 1.65 to 1.69.
- Specific Gravity: 3.34 to 3.37.
- Chemical Formula: (Mg,Fe)₂SiO₄.
Due to its lack of cleavage, peridot is more durable than gems of similar hardness that possess cleavage planes. However, its hardness of 6.5-7 means it can still be scratched by materials harder than it, such as topaz or corundum (ruby and sapphire). Care should be taken to prevent knocking or scraping the stone during daily wear.
History, Lore, and Symbolism
The word "peridot" is derived from the Arabic faridat, meaning "gem." Its history is rich with protective and healing beliefs. Ancient Egyptians valued it not only for its beauty but also for its perceived ability to protect against evil spirits and nightmares. It was often set in gold and worn as an amulet. In medieval times, peridot was associated with the sun and was believed to bring happiness, strength, and vitality to its wearer. Its luminous green hue has long been associated with renewal, abundance, and light, making it a gem of positivity and growth.
Care and Cleaning
To maintain the brilliance of a peridot, it is best cleaned with warm, soapy water and a soft brush. Ultrasonic and steam cleaners should be avoided, as the stone's chemical composition can make it susceptible to thermal shock. Given its relative softness compared to diamonds or sapphires, it is advisable to store peridot jewelry separately to prevent scratching by harder gems.
Spinel: The Great Imposter
Spinel is a gemstone that has historically lived in the shadow of more famous stones, particularly ruby. For centuries, magnificent red spinels were mistaken for rubies, earning them a place in royal regalia and lore. It was not until 1783 that spinel was formally recognized as a distinct mineral species, separate from corundum. Its addition as an official August birthstone in 2016 by the American Gem Trade Association (AGTA) and the Jewelry Industry Council brought long-overdue recognition to this durable and brilliant gem.
Geological Formation and Sources
Spinel is a magnesium aluminium oxide with the chemical formula MgAl₂O₄. It forms under high-temperature, low-pressure conditions in metamorphic rocks, often alongside corundum and other minerals. Its formation process is what allows it to grow in large, well-formed crystals, some of which have been cut into exceptionally large stones.
The most famous source for red spinel is the Badakhshan region of Afghanistan, which has been a primary source for over a millennium. The "Black Prince's Ruby," a 170-carat spinel that is part of the British Imperial State Crown, originated from this region. Other significant sources include Tajikistan, Myanmar, Sri Lanka, and Vietnam. Pink, blue, and purple spinels are also highly valued and are sourced from Vietnam, Tanzania, and Sri Lanka, among other locations.
Gemological Properties
Spinel possesses excellent physical properties that make it an outstanding choice for jewelry, especially rings. It is often considered a "forgotten" gem due to its durability and beauty.
- Hardness: 8 on the Mohs scale.
- Crystal System: Cubic.
- Refractive Index: 1.718.
- Specific Gravity: 3.60.
- Chemical Formula: MgAl₂O₄.
One of spinel’s most attractive features is its lack of cleavage, which, combined with its hardness of 8, gives it excellent toughness. This makes it highly resistant to chipping and breaking, ideal for rings and bracelets that are subject to daily wear. Spinel is also available in a wide range of colors, including the coveted "ruby-red," as well as vibrant pinks, rich blues, and deep violets.
History, Lore, and Symbolism
Spinel’s history is intertwined with that of ruby. The Timur Ruby, a massive 361-carat red spinel now in the British Crown Jewels, was once thought to be a ruby. The stone’s association with royalty and its misidentification for centuries cemented its place in history, albeit under a false name.
Symbolically, spinel is associated with revitalization and energy. It is believed to help overcome lethargy and provide a boost to the wearer's physical and mental stamina. The red variety is linked to passion and life force, while the blue spinel is associated with calm and tranquility. As a modern birthstone, spinel represents resilience and the idea of finding one’s own unique identity after a long period of being in the background.
Care and Cleaning
Spinel is a very durable gemstone that is relatively easy to care for. Its hardness and lack of cleavage make it resistant to everyday wear and tear. It can be safely cleaned using warm, soapy water and a soft brush. Ultrasonic and steam cleaners are generally safe, but it is always wise to inspect the jewelry for any loose settings before using them. As with any gemstone, it is best to avoid harsh chemicals and sudden temperature changes.
Sardonyx: The Ancient Banded Gem
Sardonyx is the original birthstone for August, with a history that dates back more than 4,000 years. It is a variety of chalcedony, which is a fibrous cryptocrystalline form of quartz. Its name is derived from the Greek words sard (a reddish-brown variety of chalcedony) and onyx (meaning "veined" or "striped"). Sardonyx is characterized by its distinctive bands of reddish-brown (sard) and white or black (onyx) layers.
Geological Formation and Sources
Sardonyx forms when silica-rich water fills cavities in volcanic rock and slowly deposits layers of chalcedony. The different colors are the result of impurities present in the water during each layer's formation (iron oxide for the reddish-brown bands, and pure silica for the white bands). The contrast between the layers is what gives sardonyx its unique and striking appearance.
Historically, India was a primary source for high-quality sardonyx, particularly the white-on-black variety. The gem was also found and used extensively in ancient Rome. Today, significant sources include Brazil, Germany, and the United States.
Gemological Properties
As a member of the quartz family, sardonyx shares many properties with other varieties of chalcedony and onyx.
- Hardness: 6.5 to 7 on the Mohs scale.
- Crystal System: Trigonal (microcrystalline).
- Refractive Index: Approximately 1.54.
- Specific Gravity: 2.58 to 2.64.
- Chemical Formula: SiO₂ (Silicon Dioxide).
Its hardness is adequate for jewelry, but like peridot, it is softer than spinel and can be scratched. The distinct banding is its most defining feature, and it is often cut en cabochon (a smooth, rounded dome) to best display these layers. It can also be carved into cameos and intaglios.
History, Lore, and Symbolism
Sardonyx is steeped in ancient history. It was a favorite stone of the ancient Egyptians, Greeks, and Romans, who used it extensively for seals, signet rings, and amulets. The Romans believed that sardonyx could protect the wearer from harm and danger, making it a popular stone for soldiers going into battle. It was also associated with courage, strength, and steadfastness.
In the context of ancient religious traditions, sardonyx is considered the original birthstone of August, stemming from the descriptions of the breastplate of Aaron in the Old Testament and the foundation stones of the New Jerusalem in the Book of Revelation. It was believed to bring happiness and good fortune to the wearer, and its protective qualities were highly valued.
Care and Cleaning
Caring for sardonyx is straightforward. It can be cleaned with warm, soapy water and a soft brush. Avoid using harsh chemicals or abrasive cleaners, as these could damage the stone's surface. As with peridot, it is best to avoid ultrasonic and steam cleaners, especially if the stone has been treated or set in a delicate mounting. Store sardonyx jewelry separately to prevent scratching by harder stones.
Conclusion
The three birthstones of August—Peridot, Spinel, and Sardonyx—offer a remarkable range of choices that appeal to diverse tastes and preferences. Peridot, with its single-hue green brilliance and extraterrestrial origins, speaks to those who appreciate unique natural phenomena and a connection to the sun. Spinel, the durable and brilliant gem, offers a rainbow of colors and a compelling history of masquerading as royalty, making it a sophisticated choice for the modern consumer. Sardonyx, the ancient banded stone, connects the wearer to millennia of human history, symbolizing courage and protection.
Whether one is drawn to the vibrant lime green of peridot, the fiery reds and pinks of spinel, or the classic, layered bands of sardonyx, August-born individuals are fortunate to have such a rich and varied selection. Each stone not only possesses its own distinct beauty and set of physical properties but also carries a wealth of historical lore and symbolic meaning, making them far more than mere decorative objects. They are tangible links to the Earth’s depths, to ancient cultures, and to the cosmos itself.