August is the only month in the calendar that proudly boasts three official birthstones: peridot, spinel, and sardonyx. Each of these gemstones carries a unique color palette, rich historical significance, and fascinating geological origins. While the query focuses on their colors, the full story of August’s birthstones extends into their cultural lore, symbolic meanings, and modern-day appeal. This article explores the color variations, gemological properties, historical use, and cultural symbolism of these three August birthstones, drawing exclusively from the provided sources.
Introduction
August’s birthstones—peridot, spinel, and sardonyx—are a diverse group that spans from vivid green to deep red and striking banded patterns. Peridot, the most well-known, is celebrated for its green hues, ranging from lime green to olive green, and even yellowish-green tones. Spinel, once mistaken for ruby and other red gems, appears in vibrant reds, purples, and blues. Sardonyx, a composite of sard and onyx, is distinguished by its banded layers of brownish-red and white or black.
These gemstones have been treasured for millennia, from ancient Roman seals to medieval shrines and modern jewelry. Understanding their colors, origins, and symbolism not only adds to their allure but also highlights the deep connection between gemstones and human history.
History and Lore
Sardonyx: The Oldest August Birthstone
Sardonyx is the oldest known August birthstone, with a history that stretches back over 4,000 years. This gemstone is composed of two types of chalcedony—sard, a reddish-brown quartz, and onyx, a banded form of quartz. The alternating layers of these materials create a unique, striped appearance.
Ancient Romans used sardonyx extensively for seals and signet rings, as it was believed that the stone’s surface would not cause hot wax to stick. The stone was also popular for cameos and intaglios, where the contrast between the bands allowed for intricate carvings.
Historical records suggest that sardonyx was one of the stones used in the High Priest’s breastplate as described in the Old Testament. This association with religious and spiritual authority elevated its status.
Roman soldiers believed sardonyx brought good luck and protection in battle, and it was widely worn as rings, bracelets, earrings, and lockets in both Egypt and Greece. Even today, sardonyx is believed to symbolize spirituality, open communication, prosperity, and courage. It is also associated with harmonious relationships, whether romantic, platonic, or professional.
Peridot: The "Evening Emerald"
Peridot, the most widely recognized August birthstone, has a long and storied history. It is the yellowish-green to greenish-yellow gem variety of olivine, a mineral composed of magnesium-iron silicates. The green color of peridot is due to the presence of iron in the crystal structure.
Peridot has often been mistaken for emerald or topaz. The Red Sea island of Topazios, where the name "topaz" is believed to originate, actually produced peridot. Historians have even speculated that Cleopatra’s famous emerald collection may have been largely made up of peridot, not emerald.
The ancient Egyptians called peridot the “gem of the sun”, and the Romans referred to it as the “evening emerald” because its green color remained visible even at night. Peridot was also used in religious artifacts; for instance, the Shrine of the Three Holy Kings in Germany’s Cologne Cathedral is adorned with 200 carats of peridot, previously believed to be emerald.
Peridot has also been found in pallasite meteorites, some of which are 4-5 billion years old. In 2005, peridot was even discovered in comet dust from the Stardust robotic space probe, making it one of the few gemstones with a cosmic origin.
Spinel: The Misunderstood Gem
Spinel is a lesser-known but equally beautiful August birthstone. For centuries, it was mistaken for ruby and other red gems due to its similar appearance. It wasn’t until the 20th century that spinel was correctly identified as a distinct mineral.
Spinel can appear in a wide range of colors, including red, purple, blue, and even pinkish or orangy hues, depending on the trace elements present. A 2007 discovery in Tanzania of pinkish and orangy red spinel generated excitement in the gem trade and among collectors.
Spinel is valued today for its vibrant colors and durability, making it an excellent alternative to ruby for those seeking a rare but affordable gemstone. It is also associated with protection, emotional strength, and clarity, and its recent rise in popularity has made it a favored choice in modern jewelry design.
Geological Formation and Sources
Peridot: From Earth’s Mantle to Meteorites
Peridot is a gem-quality transparent variety of olivine, a mineral formed under high-pressure, high-temperature conditions deep within the Earth’s mantle. It is brought to the surface through volcanic activity, where it becomes embedded in hardened lava.
Notably, peridot can also be found in meteorites, particularly pallasite meteorites, which are composed of olivine crystals embedded in nickel-iron. The presence of peridot in space rocks underscores its extra-terrestrial origins.
Historically, Zabargad Island in the Red Sea (also known as St. John’s Island) was the primary source of peridot. This small, arid island is one of the few places where peridot is found in commercial quantities. The gem crystals found there are often embedded in rock fissures and can range in size from millimeters to several centimeters.
Other notable sources of peridot include Norway, Brazil, China, Kenya, Sri Lanka, Australia, Mexico, and the Mogok district of Myanmar. In the United States, the San Carlos Indian Reservation in Arizona is known for producing small peridot crystals.
Peridot is also found in comet dust, as evidenced by the Stardust mission, where peridot was identified in material collected from a comet’s tail.
Spinel: A Diverse and Durable Gem
Spinel is a silicate mineral that forms in mafic igneous rocks, particularly basalt and gabbro, which are rich in iron and magnesium. The presence of trace elements like chromium, iron, and titanium determines its color variation.
The 2007 discovery in Tanzania brought attention to spinel’s color diversity, with pinkish and orangy red varieties capturing the interest of gem collectors. Spinel is also found in purple and blue hues, making it a versatile gemstone.
Spinel is relatively hard, with a Mohs hardness of 8, making it suitable for rings and other jewelry. However, it can be sensitive to high heat, which may cause color fading in some varieties.
Sardonyx: The Banded Chalcedony
Sardonyx is a type of chalcedony, a cryptocrystalline quartz composed of sard and onyx. Sard is a reddish-brown quartz, while onyx is a banded quartz with white or black layers.
Sardonyx is mined in various locations around the world, including India, Brazil, and Africa, where it is extracted from quartz-rich sedimentary deposits. The stone is valued for its natural banding, which makes it ideal for cameos and intaglios.
Its durability and affordability have kept it popular for centuries, and it remains a symbol of protection and good luck in many cultures.
Gemological Properties
Peridot
- Chemical Formula: (Mg,Fe)₂SiO₄
- Color: Yellowish green to greenish yellow (olive to lime green)
- Hardness: 6.5–7 on the Mohs scale
- Crystal System: Orthorhombic
- Refractive Index: 1.65–1.69
- Luster: Vitreous
- Transparency: Transparent to translucent
- Double Refraction: High (visible as two reflections of pavilion facets)
- Inclusions: Common, including needle-like inclusions and fractures
- Special Properties: High double refraction, not light-dependent (color remains consistent in all lighting)
Spinel
- Chemical Formula: MgAl₂O₄ (magnesium aluminum oxide)
- Color: Red, purple, blue, pink, orange
- Hardness: 8 on the Mohs scale
- Crystal System: Isometric
- Refractive Index: 1.718–1.724
- Luster: Vitreous
- Transparency: Transparent
- Inclusions: Rare, as it is a single crystal without cleavage
- Special Properties: Stable in light and chemicals; sensitive to high heat
Sardonyx
- Chemical Formula: SiO₂ (silicon dioxide)
- Color: Bands of brownish-red sard and white or black onyx
- Hardness: 6.5–7 on the Mohs scale
- Crystal System: Trigonal
- Luster: Waxy to vitreous
- Transparency: Translucent
- Inclusions: Minimal; may contain natural banding and imperfections
- Special Properties: Ideal for carving due to its banding
Symbolism and Metaphysical Beliefs
Peridot
Peridot is often associated with joy, good luck, and emotional healing. It is believed to ward off negative thoughts and worries, making it a popular choice for those seeking emotional balance and positivity.
The ancient Egyptians believed peridot had healing properties and called it the “gem of the sun”, associating it with divine energy and vitality. The Romans, on the other hand, referred to it as the “evening emerald” due to its ability to glow in low light.
Peridot is also the traditional gift for a 15th wedding anniversary, symbolizing long-lasting love and emotional harmony.
Spinel
Spinel is a stone of protection and emotional strength. Historically, it was believed to ward off nightmares and negative energies, making it a reassuring gemstone for those seeking emotional clarity and stability.
Its vibrant colors are said to energize the spirit, while its durability mirrors the resilience it is believed to impart to its wearer. Spinel is also associated with fearlessness and courage, making it a symbol of strength in adversity.
Sardonyx
Sardonyx is a stone of communication and protection. Its banded layers are said to represent the balance between action and rest, encouraging discipline and perseverance.
Historically, sardonyx was used as a protective amulet, especially for travelers and warriors. It was believed to bring good luck and ward off evil influences. The stone is also associated with emotional healing and spiritual growth, making it a favored gemstone for those on a journey of self-discovery.
Care and Cleaning
Peridot
Peridot has a Mohs hardness of 6.5–7, making it relatively durable but still susceptible to scratches and fractures. It should be cleaned with warm soapy water and a soft brush, as ultrasonic and steam cleaners may damage the stone if it contains inclusions or fractures.
Peridot is not light-sensitive, so it does not fade with exposure to sunlight. However, it should be stored separately from harder gemstones to prevent abrasions.
Spinel
Spinel has a hardness of 8, making it durable and suitable for everyday wear. It can be cleaned using ultrasonic and steam cleaners, but high heat should be avoided, as it may cause color fading in some varieties.
Spinel is stable in light and chemicals, making it a low-maintenance gemstone. It should be stored in a soft cloth or jewelry box to prevent scratches.
Sardonyx
Sardonyx has a hardness of 6.5–7, making it relatively hard but still prone to scratches. It is ideal for carvings and cameos, and its banding makes it easy to identify.
Sardonyx can be cleaned with warm soapy water, but harsh chemicals and ultrasonic cleaners should be avoided, as they may damage the natural banding or surface polish.
Conclusion
August’s birthstones—peridot, spinel, and sardonyx—are a rich and diverse collection that reflects the beauty and history of gemstones. From peridot’s vivid green hues and cosmic origins to spinel’s vibrant colors and recent rise in popularity, and sardonyx’s banded patterns and ancient significance, each gemstone has a unique story to tell.
Whether you are drawn to the symbolic meanings, historical significance, or gemological properties of these stones, they offer something for every gemstone enthusiast. As August’s birthstones, they continue to capture the imagination of jewelers, collectors, and those who celebrate the beauty of nature’s creations.