The eighth month of the year, August, is uniquely represented by three distinct official birthstones: Peridot, Spinel, and Sardonyx. This trio offers a remarkable spectrum of color, history, and geological origin, setting it apart from months with a single gem. Peridot, with its signature yellow-green hue, is the primary and most widely recognized August birthstone, symbolizing growth and prosperity. Spinel, often mistaken for ruby throughout history, provides a brilliant array of colors from vivid blue to deep red. Sardonyx, the most ancient of the three, is a banded variety of chalcedony that dates back millennia. Together, these stones provide a rich palette for jewelry and a deep well of lore for collectors and enthusiasts. This article explores the history, geological formation, gemological properties, and cultural significance of each of August's three birthstones, drawing from authoritative sources to provide a comprehensive guide for gemstone lovers, students of gemology, and those seeking the perfect August gift.
History and Lore
The history of August's birthstones is a tapestry of ancient trade, geological discovery, and evolving cultural significance. Each stone carries a legacy that spans centuries and continents.
Peridot holds a particularly intriguing history, often confused with other precious gems. The word "peridot" is believed to originate from the Arabic faridat, meaning "gem." Throughout history, peridot has been mistaken for topaz and emerald. The Red Sea island of Topazios, a purported source of the name "topaz," was actually a source of peridot. Perhaps the most famous historical example of this confusion is the collection of gems in Germany’s Cologne Cathedral. The Shrine of the Three Holy Kings is decorated with 200 carats of gems that were long believed to be emeralds but are, in fact, peridot. Some historians even speculate that Cleopatra's famous emerald collection may have been comprised of peridot. This gemstone was valued in many ancient and medieval cultures, prized for its unique color and supposed protective qualities.
Spinel has a history of being underappreciated, often living in the shadow of ruby. For centuries, magnificent red spinel gems were mistaken for rubies. The most famous example is the "Black Prince's Ruby" in the British Imperial State Crown, which is actually a large red spinel. It was only in the late 18th century that spinel was recognized as a distinct mineral species. This gemstone was traditionally associated with various metaphysical beliefs, including promoting reconciliation and easing sadness. Its recent inclusion as an official birthstone has brought it renewed attention as a vibrant and durable alternative to ruby.
Sardonyx is the most ancient of the three August birthstones, with a history that dates back over 4,000 years. A banded variety of chalcedony, it was a popular stone for Roman seals and signet rings. Its physical properties—specifically, its resistance to hot wax—made it ideal for this purpose. Ancient civilizations valued sardonyx for its protective qualities, often engraving it with images of gods or heroes to serve as amulets. Its use in cameos and intaglios continued through the Renaissance and into the modern era, cementing its place in the history of decorative arts.
The modern designation of these three stones as August's birthstones is a relatively recent development. Peridot has long been associated with the month, but the official list has evolved. Spinel was added to the official list of modern birthstones in 2016, while Sardonyx is recognized as the traditional or alternative birthstone. This evolution reflects a growing appreciation for the diversity and history of gemstones beyond the classic "big four" (diamond, ruby, sapphire, emerald).
Geological Formation and Sources
The three August birthstones originate from vastly different geological environments, from the deep Earth's mantle to hydrothermal veins and volcanic flows.
Peridot is unique among gemstones for its formation deep within the Earth. Unlike most gemstones that form in the Earth's crust, peridot originates in the upper mantle, forming over millions of years under extreme heat and pressure. It is then brought to the surface by volcanic activity, often found within hardened lava. In some rare cases, peridot has been found in meteorites that have traveled from outer space, making it one of the few gems that can be extraterrestrial in origin. Major sources of peridot include Pakistan, the United States (Arizona), and Myanmar. The gemstone is known for its natural lustrous quality, with some localities producing gems that are so naturally polished they are described as "spirit polished."
Spinel forms in metamorphic rocks and alluvial deposits. It is typically found in regions with complex geological histories involving high heat and pressure. Key sources for spinel include Myanmar, which has been a historical source for large, high-quality red spinels. The Luc Yen region in northern Vietnam has produced spinel in deep red, purple, pink, violet, and violet-blue hues since the 1980s, with vivid blue spinels discovered there in the 2000s. Access to these mines is challenging, often requiring a long drive from Hanoi followed by hiking or biking. A significant 2007 discovery in Tanzania yielded pinkish and orangy red spinel, captivating gem collectors. Mines in Tanzania also produce spinel in purple and blue hues. These sources highlight spinel's global distribution and the difficulty of accessing some of its most prized deposits.
Sardonyx is a variety of cryptocrystalline quartz, specifically a banded form of chalcedony. It forms in volcanic and sedimentary rocks where silica-rich solutions deposit layers of sard (brownish-red to brown to dark orange chalcedony) and onyx (typically white or black chalcedony) in alternating bands. This banded formation is what gives sardonyx its distinctive appearance. While specific modern mining locations for sardonyx are less prominently documented in contemporary gemological reports compared to peridot and spinel, its historical significance is tied to ancient sources in regions such as India and the Middle East, from which it was traded throughout the ancient world.
Gemological Properties
Understanding the physical and chemical properties of these gems is essential for identification, valuation, and care. The following table summarizes key gemological data for Peridot, Spinel, and Sardonyx.
| Property | Peridot | Spinel | Sardonyx |
|---|---|---|---|
| Mineral Species | Olivine | Spinel | Chalcedony (Cryptocrystalline Quartz) |
| Chemical Formula | (Mg, Fe)₂SiO₄ | MgAl₂O₄ | SiO₂ |
| Crystal System | Orthorhombic | Cubic | Trigonal (macrocrystalline quartz); Chalcedony is microcrystalline |
| Mohs Hardness | 6.5 - 7 | 8 | 7 |
| Refractive Index | 1.65 - 1.69 | 1.71 - 1.73 | 1.53 - 1.54 |
| Specific Gravity | 3.27 - 4.37 | 3.58 - 3.61 | 2.57 - 2.64 |
| Typical Colors | Yellowish-green to greenish-yellow | Wide range: red, pink, orange, purple, blue, black, white | Bands of brownish-red, brown, dark orange, white, and black |
Peridot (Olivine): As the gem variety of olivine, peridot's color ranges from yellowish-green to greenish-yellow, with the most valued hues being a rich olive green. Its hardness of 6.5 to 7 on the Mohs scale makes it suitable for most jewelry, though it requires some care to avoid scratching. It is one of the few gems that occurs in only one color (green), though the intensity can vary. Its refractive index and specific gravity are relatively high for a non-quartz gemstone.
Spinel: Spinel's remarkable durability, with a hardness of 8 on the Mohs scale, makes it an excellent choice for rings and other jewelry that will endure daily wear. It is stable when exposed to light and most chemicals, though high heat can cause some colors to fade. Its wide color range, from the coveted red (often mistaken for ruby) to vibrant blues, pinks, and purples, is due to trace elements like chromium, iron, and cobalt. Its cubic crystal system and high refractive index give it a brilliant sparkle.
Sardonyx: As a variety of chalcedony (cryptocrystalline quartz), sardonyx has a hardness of 7, making it durable for carving and jewelry. Its specific gravity and refractive index are lower than those of peridot and spinel, consistent with its quartz composition. The gem's defining characteristic is its banding—layers of sard and onyx that create contrasting patterns. This banded structure is what made it ideal for engraving and cameo work, as the different layers provide a natural canvas for artistic work.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, all three August birthstones are steeped in symbolism and metaphysical lore, reflecting humanity's enduring connection to the natural world.
Peridot is traditionally associated with growth, prosperity, love, loyalty, and protection. Its vibrant green color, reminiscent of spring and new life, has long been linked to vitality and renewal. In ancient times, it was believed to ward off evil spirits and nightmares. Its association with prosperity makes it a popular gift for milestone occasions. As the primary birthstone for August, it is said to bring happiness and a sense of destiny to those born in the month.
Spinel has been associated with various positive attributes throughout history. It is believed to promote reconciliation, ease sadness, and inspire a renewed sense of hope and energy. Its wide color spectrum allows different hues to carry specific meanings—red for passion, blue for tranquility, and pink for love. As a gemstone that was historically undervalued, spinel is also seen as a symbol of unappreciated beauty and the importance of seeing beyond first impressions.
Sardonyx, as one of the oldest gemstones in use, carries profound symbolism. It was considered a stone of strength, protection, and courage. Ancient warriors and leaders wore sardonyx amulets for protection in battle and to make wise decisions. The Roman belief that it could prevent the wax from sticking to seals also symbolized its power to ensure lasting and clear communication. In modern metaphysical beliefs, sardonyx is associated with stability, happiness, and marital fidelity.
For those born in August, the choice of birthstone can be personal, reflecting not only a preference for color but also an affinity for the specific meanings and histories each gem embodies.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones. Their differing physical properties require specific maintenance approaches.
Peridot (Hardness: 6.5-7) requires moderate care. While durable enough for most jewelry, it can be scratched by harder materials. It is best cleaned with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe for peridot, but steam cleaning is not recommended as it can potentially damage the stone. Avoid sudden temperature changes and harsh chemicals.
Spinel (Hardness: 8) is one of the most durable and low-maintenance gemstones. Its high hardness and good toughness make it resistant to scratching and breaking. Ultrasonic and steam cleaners are typically safe for spinel, but caution is advised if the stone has visible fractures or inclusions. Warm, soapy water with a soft brush is always a safe and effective method for cleaning. As noted, high heat can cause some colors to fade, so it should be kept away from intense heat sources.
Sardonyx (Hardness: 7) is relatively durable but, as a form of chalcedony, it can have natural fissures. It should be cleaned with warm, soapy water and a soft cloth or brush. Ultrasonic cleaners are generally not recommended for sardonyx, as vibrations could potentially loosen the stone or damage any fractures. Steam cleaning should also be avoided. Store sardonyx jewelry separately from harder stones to prevent scratching.
For all three gems, it is advisable to remove jewelry before engaging in activities that could subject it to hard blows or harsh chemicals, such as gardening, heavy cleaning, or sports.
Conclusion
August's trio of birthstones—Peridot, Spinel, and Sardonyx—offers an exceptional diversity that reflects the richness of the natural world and human history. Peridot, with its deep-earth origins and vibrant green hue, symbolizes growth and prosperity. Spinel, a gem of remarkable durability and a spectrum of colors, has emerged from the shadow of ruby to claim its own celebrated status. Sardonyx, the ancient banded chalcedony, connects the present to millennia of human artistry and belief. Together, they provide a wealth of options for those born in August, allowing for personal expression through color, history, and meaning. Whether chosen for its scientific intrigue, its historical depth, or its metaphysical properties, each of these stones carries a legacy that makes it a worthy symbol for the month of August.