August is a unique month in the world of birthstones, distinguished by its trio of official gems: peridot, spinel, and sardonyx. While many months are associated with a single stone, August offers a diverse palette of colors, histories, and symbolism. This variety provides August-born individuals with a choice that can reflect personal taste, style, and the rich tapestry of gemological lore. The three stones represent a fascinating spectrum—from the vibrant, sunlit green of peridot, through the fiery sparkle of spinel, to the earthy, banded strength of sardonyx. Each gemstone carries its own distinct narrative, geological origin, and cultural significance. This article will delve into the history, properties, sources, and symbolism of these three remarkable birthstones, providing a comprehensive guide for gemstone enthusiasts, jewelry buyers, and students of gemology.
The tradition of birthstones has deep historical roots, with early concepts tracing back to the ancient Breastplate of Aaron described in the Bible’s Book of Exodus, which featured twelve gemstones representing the tribes of Israel and, later, the months of the year. The modern birthstone concept began to crystallize in the 18th century in Poland, where Jewish gem traders started associating specific stones with each month. The official list of birthstones has evolved over time, with additions and changes reflecting gemstone availability and market preferences. For August, the journey to its current trio is particularly illustrative of this evolution. While peridot has long been recognized as the traditional August birthstone, sardonyx holds a place of ancient significance, and spinel was officially added to the list in 2016, offering a modern alternative with a storied past.
History and Lore
The historical journey of each August birthstone is distinct, reflecting centuries of human fascination with these minerals.
Peridot: The Ancient Gem of the Pharaohs
Peridot’s history is one of profound antiquity and frequent misidentification. The gemstone is the yellowish-green to greenish-yellow variety of the mineral olivine. The word “peridot” is believed to derive from the Arabic faridat, meaning gem. This August birthstone was valued in many ancient and medieval cultures. Its most famous historical source is the Red Sea island of Topazios, a location that actually produced peridot but gave its name to the gemstone topaz. This confusion is part of a broader historical pattern; peridot has often been mistaken for other gems, most notably emerald.
Some historians speculate that Cleopatra’s legendary collection of emeralds may have actually been composed of peridot. This belief is supported by the discovery of large peridot crystals in Egypt, which were mined on the island of Zabargad. The gem’s allure extended beyond the Mediterranean. In Germany’s Cologne Cathedral, the Shrine of the Three Holy Kings is adorned with 200 carats of gems long believed to be emeralds. Modern analysis has confirmed these gems are, in fact, peridot, the August birthstone. This example underscores the historical challenge of distinguishing between green gemstones before modern gemological tools were available.
Spinel: The Great Impersonator
Spinel’s history is intrinsically linked to its remarkable similarity to other, more famous red gemstones. For centuries, red spinel was mistaken for ruby, earning it the nickname “the great impostor.” Some of the world’s most famous “rubies” are, in fact, spinel. The most notable example is the Black Prince’s Ruby, a massive red gem set in the British Imperial State Crown. This stone, along with the Timur Ruby, was historically considered a ruby but is now known to be a red spinel. This long history of misattribution led to spinel being underappreciated for much of its history. It was only relatively recently that spinel began to gain recognition in its own right as a beautiful and valuable gemstone, particularly as consumers seek alternatives to ruby. Its official addition to the August birthstone list in 2016 reflects this growing appreciation and its historical connection to the month.
Sardonyx: The Original August Stone
Sardonyx is the original August birthstone, with a history that dates back more than 4,000 years. This banded variety of onyx, composed of alternating layers of sard (a reddish-brown chalcedony) and onyx (a black or white chalcedony), has been used for carving and jewelry since antiquity. Its durability and striking contrast made it a favorite for cameos and intaglios—carved gemstones used for seals and decorative objects. In ancient Rome and Greece, sardonyx was highly prized for signet rings, as its bands could be arranged to create dramatic scenes or patterns. Its use in the Breastplate of Aaron further cemented its ancient and sacred significance. While less common in modern jewelry than peridot or spinel, sardonyx maintains its status as the traditional stone for August, valued for its historical continuity and unique appearance.
Geological Formation and Sources
The origins of these three gemstones are as varied as their histories, spanning the Earth’s mantle, volcanic activity, and even outer space.
Peridot: From the Mantle to Meteorites
Peridot has one of the most extraordinary formation stories of any gemstone. It is formed under extreme conditions deep within the Earth’s mantle. Unlike many gemstones that form in the crust, peridot is brought to the surface by volcanic activity. It can be found in the hardened lava that carries it from deep within the Earth. Furthermore, peridot is the only gemstone found in meteorites that have traveled from outer space. These extraterrestrial peridots provide a tangible link between our planet and the cosmos. Major sources of peridot include Egypt (particularly the island of Zabargad), Pakistan, Myanmar, and the United States (Arizona and New Mexico). The gem’s formation in the mantle and its delivery via lava flows make its geological story unique among birthstones.
Spinel: A Mineral of Many Colors
Spinel is a magnesium aluminum oxide mineral that crystallizes in the cubic system. It forms in a variety of geological environments, most commonly in metamorphic rocks and alluvial deposits. Historically, the most famous source of red spinel was the Badakhshan region in Afghanistan and Tajikistan, which produced the large crystals that were often mistaken for rubies. Other significant sources include Myanmar (Burma), Sri Lanka, and Vietnam. Spinel occurs in a wide range of colors beyond red, including pink, blue, violet, and black. The red variety is the most prized for jewelry, but the gem’s diversity in color has contributed to its growing popularity as a birthstone.
Sardonyx: A Product of Silica Deposition
Sardonyx is a variety of chalcedony, which is a microcrystalline form of quartz (silicon dioxide). Its distinctive banding is formed by the slow deposition of silica in layers, with alternating colors of sard and onyx. This process typically occurs in volcanic cavities or geodes. Sardonyx is found in various locations around the world, including India, Brazil, Germany, and the United States. The quality of the banding—its contrast, straightness, and regularity—determines the gem’s value for carving and jewelry. Unlike peridot and spinel, sardonyx does not have a single famous source; it is more widely distributed, reflecting its formation in silica-rich environments.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is essential for identification, valuation, and care. The following table summarizes key gemological data for peridot, spinel, and sardonyx.
| Property | Peridot | Spinel | Sardonyx |
|---|---|---|---|
| Mineral Family | Olivine | Spinel | Chalcedony (Quartz) |
| Chemical Formula | (Mg, Fe)₂SiO₄ | MgAl₂O₄ | SiO₂ (with iron oxide impurities) |
| Crystal System | Orthorhombic | Cubic | Trigonal (microcrystalline) |
| Hardness (Mohs) | 6.5 - 7 | 8 | 7 |
| Refractive Index | 1.65 - 1.69 | 1.71 - 1.73 | 1.53 - 1.54 |
| Specific Gravity | 3.34 | 3.58 - 3.61 | 2.65 |
| Typical Colors | Yellowish-green to greenish-yellow | Wide range: red, pink, blue, violet, black | Bands of reddish-brown (sard) and black/white (onyx) |
| Luster | Vitreous (glass-like) | Vitreous | Vitreous to waxy |
Peridot Properties
Peridot’s signature color ranges from yellowish-green to greenish yellow, caused by the presence of iron. Its hardness of 6.5 to 7 on the Mohs scale makes it suitable for most jewelry, though it can be susceptible to scratching and chipping with rough wear. It has a vitreous luster and a refractive index between 1.65 and 1.69. Peridot is not typically treated or enhanced, making it a popular choice for those who prefer natural gemstones. Its inclusions are common but are often accepted as part of the stone’s character.
Spinel Properties
Spinel is renowned for its excellent hardness of 8 on the Mohs scale, making it very durable and resistant to scratching. It has a high refractive index (1.71–1.73) and strong dispersion, which gives it a brilliant sparkle similar to diamond. Spinel occurs in a vast array of colors, with the red variety being the most valuable. It is generally untreated, though some blue spinels may be heat-treated to enhance color. Its cubic crystal system gives it a single refractive index, a key identifying feature.
Sardonyx Properties
Sardonyx, as a variety of chalcedony, has a hardness of 7 on the Mohs scale, making it durable for everyday wear. It has a lower refractive index (1.53–1.54) and a waxy to vitreous luster. Its defining characteristic is the sharp, parallel banding of reddish-brown sard and black or white onyx. The value of sardonyx in jewelry and carving is highly dependent on the quality and contrast of these bands. It is not typically treated, though some commercial sardonyx may be dyed to enhance the color contrast.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, each August birthstone carries a legacy of symbolic meaning and metaphysical belief, often rooted in ancient traditions and modern crystal healing practices.
Peridot: The Stone of the Sun
Peridot has long been associated with light, warmth, and protection. Ancient cultures believed it could ward off nightmares and bring happiness and strength to the wearer. Its vibrant green color is often linked to growth, renewal, and prosperity. In metaphysical circles, peridot is considered a stone of compassion and is believed to alleviate stress, anger, and jealousy, promoting emotional balance and well-being. Its connection to the sun makes it a symbol of vitality and positive energy.
Spinel: The Stone of Immortality and Renewal
Historically, spinel was believed to offer protection and was associated with immortality and renewal. Its resemblance to ruby led it to share some of ruby’s symbolic properties, such as passion and vitality. In modern metaphysical beliefs, spinel is considered a stone of revitalization, said to energize and rejuvenate the wearer. Different colors of spinel are associated with different chakras; for example, red spinel is linked to the root chakra for grounding, while blue spinel is connected to the throat chakra for communication.
Sardonyx: The Stone of Strength and Protection
Sardonyx, with its ancient history as a stone for seals and amulets, has traditionally been a symbol of strength, courage, and protection. In ancient Rome, warriors wore sardonyx talismans for protection in battle. Its banded structure is often interpreted as representing the balance between opposing forces. In crystal healing, sardonyx is believed to promote discipline, integrity, and perseverance. It is said to help overcome negative thoughts and fears, fostering a sense of stability and confidence.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones. Their different hardness and chemical compositions dictate specific cleaning methods and precautions.
Caring for Peridot
With a hardness of 6.5 to 7, peridot requires some care to avoid scratches. It is best to clean peridot jewelry using warm, soapy water and a soft brush. Avoid ultrasonic cleaners, as the vibrations can cause damage, especially if the stone has inclusions. Steer clear of harsh chemicals, including household cleaners and cosmetics, which can etch the surface. Store peridot separately from harder gems to prevent scratching.
Caring for Spinel
Spinel’s high hardness of 8 makes it relatively easy to care for. It can be safely cleaned with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe for untreated spinel, but caution is advised for stones with inclusions or fractures. Steam cleaning is also acceptable. Like peridot, it should be stored away from harder gems to avoid abrasion.
Caring for Sardonyx
As a member of the quartz family, sardonyx is durable with a hardness of 7. It can be cleaned with warm, soapy water and a soft brush. Avoid prolonged exposure to strong sunlight or heat, which could fade the color of some dyed varieties. Ultrasonic cleaners are safe for natural sardonyx but should be avoided for dyed or treated stones. Store sardonyx away from harder materials to prevent scratching.
Conclusion
August’s trio of birthstones—peridot, spinel, and sardonyx—offers a remarkable diversity that reflects the month’s vibrant energy. Peridot, with its sun-kissed green hue, carries an ancient legacy as a gem of royalty and cosmic origin. Spinel, the great survivor of historical misidentification, now shines in its own right as a durable and brilliant gem. Sardonyx, the original August stone, provides a tangible link to millennia of human artistry and symbolism. Together, they provide August-born individuals with a choice that spans the color spectrum, from green to red to banded earth tones. Whether chosen for its historical significance, metaphysical properties, or simply its aesthetic appeal, each stone serves as a unique and personal emblem of the summer month. Understanding their individual stories, properties, and care requirements allows for an informed and meaningful selection, ensuring that these gems can be cherished for generations.