For those born in the eighth month of the year, the birthstone selection is uniquely abundant and historically rich. Unlike most months that are assigned a single gem, August boasts three official birthstones: the vibrant peridot, the versatile spinel, and the ancient sardonyx. This trio offers a remarkable spectrum of color, lore, and durability, reflecting the month's own transition from the peak of summer to the promise of autumn. Each stone carries a distinct narrative, from peridot's formation in the Earth's deep mantle and extraterrestrial origins to spinel's long history of being mistaken for ruby, and sardonyx's legacy as a talisman of strength and protection spanning over four millennia. This article provides a detailed exploration of these three magnificent gems, delving into their geological origins, gemological properties, historical significance, and the symbolic meanings that have made them enduring favorites for collectors and jewelry connoisseurs.
The August Birthstone Trio: An Overview
The modern list of birthstones for August, standardized by the American Gem Trade Association (AGTA), includes peridot, spinel, and sardonyx. This selection provides a diverse palette, from the brilliant greens of peridot to the fiery reds of spinel and the banded earth tones of sardonyx. The inclusion of multiple stones for a single month is a relatively recent development in the long history of birthstones, offering greater choice and affordability to consumers.
Peridot is widely recognized as the primary birthstone for August, celebrated for its distinctive lime green to olive green hues. It is a gem variety of the mineral olivine, a common mineral in the Earth's mantle, which makes its occurrence in the crust somewhat unusual. Spinel, the second official birthstone, has gained significant popularity in recent decades as consumers seek alternatives to more expensive gems like ruby. For centuries, red spinel was confused with ruby, with famous examples like the "Black Prince's Ruby" in the British Imperial State Crown being, in fact, a large spinel. The third stone, sardonyx, is the original and most ancient of the August gems. It is a variety of banded chalcedony, a member of the quartz family, prized for its distinctive layers of reddish-brown sard and white onyx.
History and Lore of August's Gems
The historical journey of each August birthstone is as varied as the stones themselves, with each gem playing a unique role in different cultures and eras.
Peridot: The Ancient "Evening Emerald" Peridot has a history that stretches back to ancient Egypt, where it was mined on the island of Zabargad (now St. John's Island) in the Red Sea. The Egyptians called it the "gem of the sun" and believed it had protective qualities, warding off evil spirits, particularly at night. They valued its radiant green glow, which is visible even in low light, leading to its nickname as the "evening emerald." Peridot was also cherished by the ancient Romans, who used it for intaglios and other forms of jewelry.
Throughout history, peridot has often been mistaken for other green gems. The historical accounts of Cleopatra's famous emerald collection have led some historians to speculate that a portion of these gems may actually have been peridot. Similarly, the 200 carats of "emeralds" adorning the Shrine of the Three Holy Kings in Germany's Cologne Cathedral were later identified as peridot. This confusion highlights peridot's visual appeal and its long-standing, if sometimes unrecognized, presence in significant historical jewelry. The word "peridot" is believed to derive from the Arabic term faridat, meaning "gem," a testament to its enduring status.
Spinel: The Great Impostor Spinel's history is intrinsically linked to its resemblance to ruby. For centuries, the finest red spinels from Tajikistan and Burma were known as "Balas rubies," and many of the world's most famous "rubies" are, in fact, spinels. The aforementioned Black Prince's Ruby, a 170-carat uncut spinel, has been part of the British Crown Jewels since the 14th century. The Timur Ruby, another massive spinel, also has a long history in the collection.
The gemological distinction between spinel and corundum (ruby and sapphire) was only firmly established in the 18th century. Before this, spinel was largely considered a variety of ruby. This long history of being mistaken for its more famous cousin meant that spinel was often undervalued. However, in the 19th and 20th centuries, as gemology advanced, spinel began to be appreciated in its own right for its excellent hardness, brilliance, and wide range of desirable colors, including the coveted "hot pink" and "cobalt blue" hues.
Sardonyx: The Stone of Strength and Courage Sardonyx is by far the oldest August birthstone in terms of continuous use and significance. Its use as a carving and signet stone dates back more than 4,000 years to the early civilizations of Mesopotamia. Ancient Egyptians and Romans also highly valued sardonyx for its durability and distinctive appearance. It was a preferred material for cameos and intaglios, where the contrasting layers of color allowed artisans to create detailed, multi-toned designs.
In Roman culture, sardonyx was a talisman of strength and courage. Soldiers wore amulets of sardonyx into battle, believing it would protect them and grant them fortitude. Orators also favored the stone, associating it with persuasive speech and clear communication. Its banded nature was seen as a symbol of a life grounded in both passion (the red-brown sard layers) and purity (the white onyx layers), making it a powerful symbol for personal integrity and resilience.
Geological Formation and Mining Locations
The origins of these three gems could not be more different, ranging from the deep Earth to volcanic lava flows and hydrothermal environments.
Peridot Peridot is unique among gemstones for its formation in the Earth's mantle, the layer beneath the crust. It crystallizes under extreme heat and pressure, often at depths of 20 to 50 miles. The primary source of gem-quality peridot is brought to the surface by volcanic activity. The gem crystals can be found within the solidified lava rock or as "peridot sands" on the ocean floor, carried by currents from underwater volcanic vents.
Significant sources of peridot include: * Pakistan: The Kashmir region of Pakistan is renowned for producing large, high-quality peridot crystals with a vibrant olive-green color. * United States: Arizona is a major source, particularly the San Carlos Apache Reservation, which yields peridot in a lighter, more yellowish-green hue. * Myanmar (Burma): The Mogaung region has historically produced fine peridot. * Egypt: The ancient mines on Zabargad island are still a source of peridot, though production is limited. * China: Xinjiang province is a notable source of peridot. * Hawaii: Peridot is found in volcanic cinders, or cinders, in places like Papakolea Beach.
Interestingly, peridot has also been found in meteorites, specifically pallasite meteorites, which are remnants of early planetary formation. This extraterrestrial occurrence further enhances the gem's mystique and confirms its deep-mantle origins.
Spinel Spinel forms in metamorphic rocks and in igneous rock environments, often through the alteration of host rocks by magnesium-rich fluids. It is found in marble and in alluvial deposits, where it has been weathered from its original host rock and transported by water.
Key sources for spinel include: * Myanmar (Burma): The Mogok region is famous for producing some of the world's finest "ruby-red" spinels, as well as other colors like pink and blue. * Tajikistan: The Kuh-i-Lal region is known for its historical production of large red spinels, including the Timur Ruby. * Vietnam: Luc Yen and other areas produce high-quality spinel in a range of colors. * Sri Lanka: A traditional source for spinel, often found in alluvial gravels. * Tanzania: The Tunduru region produces spinel in a variety of colors, including vibrant pinks and blues.
Sardonyx Sardonyx is a variety of banded chalcedony, which is itself a microcrystalline form of quartz (silicon dioxide, SiO₂). It forms in low-temperature environments, typically within volcanic or sedimentary rock cavities. The distinctive bands of reddish-brown sard and white onyx are created by the successive deposition of silica layers with different impurities.
While sardonyx can be found in many parts of the world, the most historically significant sources are in India, particularly in the state of Gujarat. Other sources include Brazil, Germany, and the United States (in states like Oregon and Washington). The stone is often treated with heat or dye to enhance the contrast between its bands.
Gemological Properties
The physical and chemical characteristics of each stone dictate its durability, appearance, and care requirements. The following table summarizes the key properties of the August birthstones.
| Property | Peridot | Spinel | Sardonyx |
|---|---|---|---|
| Mineral Group | Olivine | Spinel | Chalcedony (Quartz) |
| Chemical Formula | (Mg, Fe)₂SiO₄ | MgAl₂O₄ | SiO₂ |
| Crystal System | Orthorhombic | Cubic | Trigonal (Microcrystalline) |
| Hardness (Mohs) | 6.5 – 7 | 8 | 7 |
| Refractive Index | 1.65 – 1.69 | 1.718 | 1.53 – 1.54 |
| Specific Gravity | 3.34 | 3.60 | 2.65 |
| Luster | Vitreous (Glass-like) | Vitreous | Vitreous to Waxy |
| Common Colors | Yellow-green, Olive-green, Brownish-green | Red, Pink, Blue, Violet, Black, White | Banded Reddish-brown and White |
Peridot is a relatively durable gem, suitable for most jewelry types, though its hardness of 6.5 to 7 means it can be scratched by harder materials. It lacks cleavage, making it less prone to breaking if struck, but it is sensitive to sudden temperature changes.
Spinel is an exceptionally durable gem, with a hardness of 8 on the Mohs scale and no cleavage. This makes it an excellent choice for all types of jewelry, including rings and bracelets that are subject to daily wear. Its high refractive index gives it a brilliant luster comparable to that of ruby and sapphire.
Sardonyx, with a hardness of 7, is also quite durable. As a variety of quartz, it is resistant to scratching and breaking. However, its value is often more related to the artistry of the cabochon cut or carving, which highlights its unique banding, rather than its intrinsic gemological rarity.
Symbolism and Metaphysical Beliefs
Across cultures and centuries, each of the August birthstones has been imbued with specific symbolic meanings and metaphysical properties.
Peridot: Associated with light, the sun, and prosperity, peridot is believed to bring good fortune, peace, and success to its wearer. Its vibrant green color is linked to growth, renewal, and the heart chakra. It is often called the "Stone of Joy," said to alleviate anger, jealousy, and stress, promoting emotional harmony and openness. Some beliefs hold that peridot can protect against nightmares and evil spirits.
Spinel: As the "stone of immortality," spinel is associated with revitalization and renewed energy. Its connection to ruby has lent it attributes of passion, love, and vitality. Red and pink spinels are thought to stimulate the root and heart chakras, encouraging passion and compassion. Blue spinel is associated with calm and clear communication. Historically, it was believed to aid in healing and soothe away sadness.
Sardonyx: This stone is a powerful symbol of strength, courage, and protection. Its banded structure represents the integration of different virtues. It is traditionally associated with the virtues of a noble warrior: courage, stamina, and integrity. Sardonyx is also believed to enhance willpower, discipline, and logical thinking, making it a stone for leaders, speakers, and anyone seeking to build self-confidence and overcome challenges.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones. The differences in their hardness and chemical composition require specific handling.
Peridot: Due to its moderate hardness (6.5-7) and sensitivity to thermal shock, peridot should be protected from hard knocks and extreme temperature changes. It is best cleaned with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as the vibrations and heat can cause fractures. It is also wise to avoid harsh chemicals, including household cleaners and cosmetics.
Spinel: As a very hard and durable gem (hardness 8), spinel is relatively easy to care for. It can be safely cleaned using warm, soapy water and a soft brush. It is generally stable under ultrasonic cleaners, but it is always prudent to check for any fractures or inclusions first. Steam cleaning is also usually safe, provided the stone is free of significant inclusions. Spinel is not known to be sensitive to light or chemicals.
Sardonyx: With a hardness of 7 and no cleavage, sardonyx is quite durable and low-maintenance. It can be cleaned with warm, soapy water and a soft cloth or brush. Ultrasonic and steam cleaning are typically safe for untreated sardonyx. However, if the stone has been dyed or treated to enhance its color, it is best to use only mild soap and water, as stronger cleaning methods could strip the treatment.
Conclusion
The August birthstones—peridot, spinel, and sardonyx—offer a compelling study in diversity, history, and geological wonder. From the deep-mantle origins of the brilliant green peridot to the meteoric journeys that sometimes deliver it to Earth, from the fiery red spinel that once masqueraded as a ruby to the ancient, banded sardonyx that armed Roman soldiers with courage, each gem tells a unique story. Together, they provide August-born individuals with an exceptional array of choices, whether they are drawn to the vibrant color of peridot, the brilliant durability of spinel, or the historical gravitas of sardonyx. This triad of gems not only reflects the rich tapestry of the summer month but also stands as a testament to the enduring allure and cultural significance of gemstones throughout human history.