August is uniquely distinguished in the world of gemstones by offering not one, but three official birthstones: peridot, spinel, and sardonyx. This trio provides a remarkable spectrum of color, history, and symbolism, allowing those born in the eighth month to select a gem that resonates with their personal style and spiritual inclinations. From the radiant lime-green of peridot to the vivid reds of spinel and the earthy bands of sardonyx, these stones represent a rich tapestry of geological formation, cultural lore, and modern gemological appeal. The American Gem Trade Association (AGTA) and Jewelers of America (JA) officially recognize these three gems, with peridot as the primary modern birthstone, sardonyx as the traditional stone, and spinel added as a more recent official option in 2016. This article delves into the history, properties, origins, and care of each of August's birthstones, providing a comprehensive guide for enthusiasts, collectors, and jewelry buyers.
History and Lore: A Journey Through Time
The history of August's birthstones spans millennia, with each stone carrying its own legacy of use and belief. Sardonyx stands as the most ancient of the trio. As a variety of chalcedony, it has been prized since antiquity for its distinctive banding and durability. Historical records indicate that sardonyx was particularly popular in ancient Rome for crafting seals and signet rings. Its utility was practical: the stone's surface was resistant to hot wax, making it an ideal material for imprinting official documents and correspondence. This functional use cemented its status in Roman society and beyond.
Peridot's history is equally storied, though often shrouded in confusion. The name "peridot" is believed to derive from the Arabic word "faridat," meaning gem. Throughout history, its vibrant green hue led to its frequent misidentification with other green stones, notably emerald and topaz. Many medieval European cathedral treasures that were long thought to contain emeralds have, upon modern examination, been identified as peridot. This historical mix-up underscores the stone's enduring allure and its presence in significant religious and royal collections across centuries.
Spinel's journey to becoming a recognized birthstone is more recent, yet its history is no less illustrious. For centuries, large red spinels were often mistaken for rubies due to their similar color and brilliance. Some of the world's most famous "rubies," such as the Black Prince's Ruby and the Timur Ruby in the British Crown Jewels, are actually spinels. It was only in the 19th century that gemologists began to reliably distinguish spinel from ruby based on differences in crystal structure and optical properties. The official recognition of spinel as an August birthstone by the AGTA and JA in 2016 acknowledged its historical significance, beauty, and increasing importance in the gem market, providing August-born individuals with a vibrant alternative to ruby.
The assignment of multiple birthstones for August is a modern development driven by consumer choice. The traditional list, established by the National Association of Jewellers (now the British Jewellers' Association) in 1912, included only sardonyx. Peridot was added to the official list in the United States that same year, reflecting its growing popularity and availability. Spinel's addition in 2016 expanded the color palette and options available, a trend that continues to make the August birthstone selection uniquely versatile.
Geological Formation and Sources
The diverse origins of August's birthstones contribute to their unique characteristics and global availability. Peridot is a gem-quality variety of the mineral olivine. Unlike many gemstones that derive their color from trace elements, peridot's distinctive green hue is caused by the presence of iron within its own crystal structure. This chemical composition results in a consistent color range, from yellowish-green to olive and brownish-green, depending on the iron content. Peridot forms deep within the Earth's mantle and is brought to the surface through volcanic activity. Significant sources include Pakistan, where high-quality peridot is mined from the challenging terrain of the Gilgit-Baltistan region; Myanmar; and the United States, particularly Arizona, which is known for producing peridot from volcanic rock. The gem's formation in extreme conditions and its subsequent eruption to the surface make it a fascinating subject of geological study.
Spinel is a magnesium aluminum oxide (MgAl₂O₄) and forms under similar high-temperature, low-pressure metamorphic conditions, often in association with marble. Its crystal structure is cubic, which differentiates it from the hexagonal structure of corundum (ruby and sapphire). The most prized spinel colors, such as vibrant reds and blues, come from specific localities. The Luc Yen region in northern Vietnam has been a notable source since the 1980s, producing spinel in deep red, purple, pink, violet, and violet-blue hues, with vivid blue spinels discovered in the 2000s. Access to these mines is difficult, requiring long drives and hiking, which adds to the stone's allure. Another significant source is Tanzania, where a 2007 discovery yielded captivating pinkish and orangy-red spinel, along with purple and blue varieties. Sri Lanka is also a historic source for spinel, particularly for red and blue stones. The geological conditions in these locations allow for the formation of large, clean crystals, which are highly valued in the gem trade.
Sardonyx is a cryptocrystalline variety of quartz, specifically a banded form of chalcedony. It is composed of alternating layers of sard (a brownish-red to orange variety of chalcedony) and onyx (typically a black or white variety of chalcedony). This banding occurs during the formation of the stone, as different layers of silica gel deposit in cavities or fissures. Sardonyx is found in various parts of the world, including India, Germany, Brazil, and the United States. Unlike peridot and spinel, which are often mined from hard rock, sardonyx is typically collected from sedimentary deposits or riverbeds where the nodules have been naturally eroded and transported. Its formation is a slow process, with each band representing a distinct period of deposition, creating a unique geological record within each stone.
Gemological Properties
Understanding the physical and optical properties of these gemstones is essential for their evaluation, care, and use in jewelry. The following table summarizes key gemological data for peridot, spinel, and sardonyx, based on information derived from the provided sources.
| Property | Peridot | Spinel | Sardonyx |
|---|---|---|---|
| Mineral Family | Olivine | Spinel | Chalcedony (Quartz) |
| Chemical Formula | (Mg,Fe)₂SiO₄ | MgAl₂O₄ | SiO₂ |
| Hardness (Mohs Scale) | 6.5 - 7 | 8 | 6.5 - 7 |
| Crystal System | Orthorhombic | Cubic | Trigonal (Cryptocrystalline) |
| Typical Colors | Yellowish-green to olive, brownish-green | Red, pink, orange, purple, blue, black | Bands of brownish-red, brown, dark orange, white, black |
| Refractive Index | 1.65 - 1.69 | 1.71 - 1.76 | 1.53 - 1.54 |
| Specific Gravity | 3.34 - 3.48 | 3.58 - 3.61 | 2.57 - 2.64 |
| Transparency | Transparent to translucent | Transparent to translucent | Translucent to opaque |
| Luster | Vitreous (glass-like) | Vitreous | Vitreous to waxy |
Peridot is a relatively durable gemstone with a hardness of 6.5 to 7 on the Mohs scale, making it suitable for most jewelry applications, though it can be prone to scratching if worn daily against harder materials. Its vitreous luster enhances its bright, lively color. The absence of pleochroism (the display of different colors when viewed from different angles) in peridot simplifies its cutting and ensures consistent color from all directions.
Spinel is notably durable, with a hardness of 8 on the Mohs scale, placing it among the tougher gemstones. This high hardness, combined with its lack of cleavage (a tendency to break along flat planes), makes spinel an excellent choice for rings and other jewelry that may encounter daily wear. Its cubic crystal system and high refractive index contribute to its brilliance and fire. Spinel is stable under light and most chemicals, but high heat can cause fading in some colored varieties.
Sardonyx, with a hardness of 6.5 to 7, is moderately durable but requires care to avoid chipping, especially at the edges of cabochon cuts where the banding is most prominent. As a form of quartz, it has no cleavage but exhibits conchoidal fracture. Its cryptocrystalline structure means it lacks the transparency of many other gemstones, instead being prized for its opaque, banded appearance. The distinct contrast between the sard and onyx layers is its defining feature, creating unique patterns in every stone.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, August's birthstones are rich in symbolic meaning and metaphysical lore, which have been attributed to them across various cultures and eras.
Peridot is strongly associated with positive emotions and healing. It is often called the "stone of the sun" due to its radiant green color, which is believed to promote joy, abundance, and emotional clarity. In metaphysical traditions, peridot is linked to the Heart Chakra, supporting emotional healing, releasing negative patterns, and opening the heart to love and forgiveness. It is also thought to bring good luck, peace, and success, making it a popular talisman for personal growth and prosperity.
Spinel is celebrated for its energizing and revitalizing properties. Its wide range of colors is said to correspond to different energetic qualities, but overall, spinel symbolizes inspiration, energy, and resilience. It is considered a stone of renewal and vitality, helping to restore energy levels and inspire hope during challenging times. Some traditions associate spinel with grounding and encouragement, making it a supportive gem for those seeking to overcome obstacles or embark on new ventures.
Sardonyx, as the most ancient of the trio, is deeply connected to themes of strength, stability, and protection. Historically, it was used for amulets and seals, believed to ward off evil and provide courage. In modern metaphysical beliefs, sardonyx is thought to promote steadfastness, discipline, and secure relationships. Its earthy, banded appearance is said to help ground one's energy, fostering a sense of security and inner strength. It is often recommended for those seeking protection, both physically and emotionally.
These symbolic meanings add a layer of personal significance to jewelry featuring these stones, allowing wearers to connect with their birthstone on a spiritual level. While these beliefs are rooted in tradition and folklore rather than scientific evidence, they continue to be an important aspect of the gemstone's cultural appeal.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of August's birthstones. The specific recommendations are based on each stone's gemological properties, particularly hardness, cleavage, and chemical stability.
Peridot requires careful handling due to its moderate hardness (6.5-7) and lack of cleavage, though it can be susceptible to scratching and chipping. It is best cleaned using warm, soapy water and a soft brush. Avoid ultrasonic and steam cleaners, as the vibrations and heat can potentially damage the stone, especially if it has inclusions or fractures. Peridot should also be protected from sudden temperature changes and harsh chemicals, including acids and strong detergents. When storing, keep it separate from other jewelry to prevent abrasion.
Spinel is one of the more durable birthstones, with a hardness of 8 and no cleavage. It can generally withstand ultrasonic and steam cleaning, provided there are no significant fractures. However, warm soapy water and a soft brush are always a safe and effective method. Spinel is stable under light and most chemicals, but high heat can cause some colors to fade, so it should be kept away from extreme temperatures. Its durability makes it suitable for everyday wear in rings, earrings, and bracelets.
Sardonyx, with a hardness of 6.5 to 7, is relatively durable but can chip if struck hard. As a form of quartz, it is resistant to most chemicals but should still be cleaned with care. Warm, soapy water and a soft brush are recommended for cleaning. Ultrasonic cleaners are generally safe, but steam cleaning is not advised due to the risk of thermal shock. Sardonyx should be stored carefully to avoid scratches from harder materials. Its banding can make it vulnerable to damage at the edges, so protective settings are advisable for rings.
In general, all three birthstones benefit from regular, gentle cleaning and proper storage. Removing jewelry before engaging in strenuous activities, household chores, or applying cosmetics can help prevent damage and preserve their luster for generations.
Conclusion
August's birthstones—peridot, spinel, and sardonyx—offer a remarkable diversity that reflects the richness of the natural world and human history. From the volcanic origins of peridot to the metamorphic formations of spinel and the sedimentary layers of sardonyx, each stone tells a unique geological story. Their histories are intertwined with ancient civilizations, from Roman seals to medieval treasures, and their modern recognition by gemological authorities highlights their enduring value. The symbolic meanings attributed to each stone—joy and abundance for peridot, inspiration and resilience for spinel, and strength and protection for sardonyx—provide a personal connection for those born in August. With careful selection based on color, durability, and personal significance, and with proper care to maintain their beauty, these three gemstones offer a lifetime of enjoyment and a tangible link to the timeless allure of the earth's treasures.