In the world of gemstones, the month of August holds a particularly exciting distinction: it is the only month officially recognized with three birthstones—peridot, spinel, and sardonyx. Each of these gems carries a unique legacy, spanning geological processes, historical symbolism, and modern jewelry use. From the vivid green of peridot, found in volcanic formations and even space, to the vibrant color palette of spinel and the layered elegance of sardonyx, August’s birthstones represent a diverse and rich selection. This article delves into the properties, sources, cultural importance, and practical care of these three gemstones, drawing exclusively from authoritative and verified sources to provide a well-rounded, scholarly exploration.
Peridot, the most widely recognized of the three August birthstones, is the gem variety of the mineral olivine. Known for its distinctive yellow to green hue, peridot forms deep within the Earth’s mantle and is brought to the surface through volcanic activity. It is also found in meteorites, making it one of the few gemstones that originate from outer space. Much of the world's peridot comes from basalt flows or volcanic regions, while the famous green sand beaches of Hawaii contain peridot sediments eroded from the surrounding rocks. As a gemstone, peridot is prized for its affordability, vibrant color, and durability, making it a popular choice in affordable jewelry.
Spinel, although less familiar than peridot, is increasingly gaining attention as a modern, versatile gemstone. In July 2016, spinel was officially recognized as an August birthstone by both the American Gem Trade Association and the Jewelers of America. Spinel is a mineral with a cubic crystal structure and is known for its wide variety of colors—ranging from red and blue to pink and black. It is also highly durable, with a hardness comparable to that of garnet and topaz, making it ideal for daily wear. Thanks to its growing prestige, spinel is considered a modern upgrade from traditional August birthstones, offering a broader spectrum of aesthetic choices and investment potential.
Sardonyx, the third gemstone associated with August, is a type of chalcedony that features distinct bands of color, typically a sandy brown or reddish brown with white layers. Unlike peridot and spinel, sardonyx is not just appreciated for its beauty but also has a long history of use in carvings and cameos. Although ancient civilizations considered onyx and sardonyx separate minerals, they are now classified as types of agate, both formed in even layers within the rock. This property makes sardonyx ideal for creating relief sculptures and cameos, a practice that reached artistic heights during the Roman Empire. It is far less costly than peridot but carries a historical nobility that enhances its appeal as a birthstone.
History and Lore
The history of the August birthstones stretches back centuries, with each stone carrying a unique narrative. Peridot was known to the ancient Egyptians, who believed the gem was brought to Earth by sun rays. They referred to it as “the gem of the sun” and were fascinated by its green color. Some of their green stones actually turned out to be peridot, which was later identified more clearly in the 17th century. Peridot was also valued by the Romans, and it was often featured in Renaissance-era jewelry and medieval rings.
Spinel's recognition as a birthstone is relatively recent, but the gem itself dates back centuries. The gem was often confused with ruby by jewelers and royalty alike, as some red spinels were as vivid and precious as rubies. The most famous example is the “Black Prince’s Ruby,” set in the UK’s Imperial State Crown, which is actually a vivid red spinel, not a ruby. This misidentification highlights spinel’s high quality and appeal, and its recent inclusion as an August birthstone demonstrates how modern gemology is restoring its rightful place in the world of fine stones.
Sardonyx has perhaps the most ancient lineage of the three. Archaeological evidence indicates that the stone was used as early as the Sumerian period, and later featured prominently in Egyptian and Roman jewelry. The Sumerians believed that onyx could bring strength and power, and similar beliefs extended to sardonyx. During the Roman era, sardonyx was used in the famous cameo portraits crafted from layered agates. This cultural and artistic legacy makes sardonyx not only a practical and beautiful August birthstone but also a gemstone that reflects the historical craft of ancient civilizations.
Geological Formation and Sources
Understanding the origins of August’s birthstones requires a basic grasp of their geological backgrounds and where they are found.
Peridot is formed under extreme heat and pressure deep within the Earth’s mantle. As magma rises to the surface, the partially melted mantle rock known as peridotite can cool quickly, forming olivine crystals, which are the source of peridot as a gemstone. When these crystals are brought to the surface by volcanic eruptions, they can be found in lava flows and basalt rock formations. Some of the finest peridot is mined from lava tubes and ancient volcanic regions, such as those found in the United States (Arizona), Egypt, and China. In addition to these terrestrial sources, peridot has also been identified in meteorites, especially in the Mesosiderite and Pallasite groups. These extraterrestrial peridots, though not typically cut into jewelry due to their rarity and small size, are valuable to both scientists and collectors.
Spinel, by contrast, forms in a different geological context. It often crystallizes in metamorphic and igneous rocks under high-temperature conditions. The most prized spinels come from regions such as Tajikistan, Burma (Myanmar), Sri Lanka, and Tanzania. These areas have produced some of the world’s most notable spinel gems, particularly in ruby-red and vivid blue varieties. Spinel is also discovered in alluvial deposits, where weathering and erosion have transported the stones from their source areas into riverbeds. These secondary sources are also commercialized and provide accessible access to fine quality spinel with rich coloration.
Sardonyx, as a type of chalcedony, forms in sedimentary environments where siliceous fluids flow through cavities and layering of minerals occurs within rock formations. It is typically found in volcanic and metamorphic rocks, where the slow, steady process of layering results in the characteristic colors and patterns of the stone. The primary sources of sardonyx are India, Brazil, and Poland, though it is also found in other regions with suitable geological conditions. The distinct coloration of sardonyx—usually a reddish-brown base color with white or light-colored bands—makes it highly desirable for carved cameos and intaglios, particularly in antique and semi-antique jewelry markets.
Gemological Properties
Each of the August birthstones possesses distinct gemological properties that influence their value, aesthetics, and practical use in jewelry.
Peridot
Peridot has a hardness of 6.5 to 7 on the Mohs scale, meaning it is relatively durable but still sensitive to scratches and abrasions. Its color ranges from light green to deep olive green, with the most valuable stones exhibiting a vivid, pure green hue without too much yellow or brown overtones. Peridot is typically transparent to translucent and has good brilliance, allowing light to pass through the stone. It is a single mineral species under the olivine family and does not come in various colors like spinel. Due to its relatively low hardness, care should be taken when setting peridot in jewelry to avoid using settings that might cause the stone to chip or wear unevenly over time.
Spinel
With a hardness rating of 8 on the Mohs scale, spinel is significantly more durable than peridot, making it an excellent choice for daily wear in rings, bracelets, and earrings. It is available in a wide array of colors, including red, blue, pink, colorless, and black. Spinel has strong luster, good dispersion, and refractive indices that contribute to a brilliant display when cut correctly. It also resists inclusions better than many other gemstones, often appearing nearly flawless. The most well-known colors are ruby-red spinel and cobalt blue spinel, both of which can rival their namesake gemstones in appearance and appeal. Spinel’s clarity and durability make it both a classic and contemporary gem choice, particularly for those seeking affordability and practicality.
Sardonyx
Sardonyx has a hardness of 6.5 to 7 on the Mohs scale, similar to peridot. It is a banded agate, featuring distinct layers that are primarily reddish-brown and white. The luster of sardonyx is waxy to dull, and it does not transmit light like transparent gems. It is opaque or translucent and offers an appealing, carved look when set into jewelry. Sardonyx is commonly used in cameos, brooches, and rings with engraved designs, especially for those who favor the artistry of relief sculptures rather than faceted gemstones. Unlike the other two August birthstones, sardonyx is not commonly used in high-fashion or modern jewelry, but it has significant historical value and is still appreciated in antique and artisanal pieces.
Symbolism and Metaphysical Beliefs
The symbolism and metaphysical beliefs surrounding the August birthstones are as rich as their geological and physical properties. Each of these gems has been viewed with curiosity and reverence by various cultures throughout history.
Peridot
Peridot is often associated with renewal, strength, and protection. Ancient civilizations, including the Vikings and Egyptians, believed it was a gem of the sun and used it in their rituals and ceremonies. The Vikings carried peridot as a protective charm on their seafaring voyages, believing it could help them avoid storms and bad luck. In medieval Europe, the stone was popular among nuns and women who avoided the use of artificial gem materials. Metaphysically, peridot is linked to cleansing and rejuvenation, and is thought to open the heart and encourage emotional healing. Modern crystal healers suggest that the green color of peridot aligns with the heart chakra and promotes a sense of inner peace and positive energy.
Spinel
Spinel has a more recent metaphysical narrative than peridot and sardonyx. While not as historically symbolic, it is now associated with vitality, positivity, and emotional healing. Red spinel is seen as a stimulating gemstone that enhances courage and vitality, much like ruby. Blue spinel, on the other hand, is thought to bring calmness, clarity, and spiritual wisdom. The gem is also associated with loyalty and trust, making it a fitting choice for romantic jewelry and personal talismans. As an officially recognized August birthstone since 2016, spinel is increasingly gaining its own set of symbolic narratives and is often used in modern jewelry for its vibrant color and uplifting energy.
Sardonyx
Sardonyx is traditionally believed to provide protection, especially in the evening and near water. It was one of the most favored stones for ancient Roman amulets and was often worn by seafarers and travelers to ward off evil. Sardonyx is also linked to discipline, focus, and ambition, making it a popular stone for those striving for success in their careers or personal goals. In medieval Europe, it was valued for its protective qualities and was used in rings and cameos for both decorative and mystical purposes. Today, sardonyx is still considered a protective stone and is especially popular in feng shui, where it is believed to enhance stability and balance in a space.
Care and Cleaning
Proper care and maintenance are essential to preserving the beauty and longevity of August’s birthstones. Each of these gemstones requires particular attention due to their distinct hardness and structural characteristics.
Peridot
Due to its relatively low hardness of 6.5 to 7 on the Mohs scale, peridot should be handled with care to avoid scratches and chips. It should not be exposed to harsh chemicals or cleaned using ultrasonic cleaners, as these can cause damage by resonating through the stone and potentially loosening the setting or affecting the integrity of the gem. A gentle cleaning method using mild soap, warm water, and a soft brush is recommended. Peridot should be stored separately from harder gemstones in a soft pouch or jewelry box to prevent scratches.
Spinel
Spinel, with a hardness of 8 on the Mohs scale, is more durable and resilient. It can typically withstand exposure to ultrasonic cleaners and steam cleaners, but some inclusions or fractures may still be vulnerable to damage. As a general rule, spinel can be safely cleaned with mild soapy water and a soft brush. Avoid using abrasive materials or harsh chemicals, especially if the stone has any surface enhancements or fractures. Spinel can be worn daily, but it should be removed before engaging in physical activities that could subject it to impact or pressure.
Sardonyx
Sardonyx, being a form of chalcedony, is also moderately hard and requires gentle cleaning. Because it is generally opaque and has a lower refractive index than transparent gemstones, it is less affected by scratches and abrasion. However, it is still vulnerable to impact fractures and should not be subjected to ultrasonic or steam cleaners, which could affect the agate layers and the stone’s setting. The best way to clean sardonyx is with warm, soapy water and a soft cloth. It should be stored away from harder gemstones to protect its surface and avoid unnecessary wear.
Conclusion
The August birthstones—peridot, spinel, and sardonyx—represent a diverse and fascinating selection that caters to varying tastes, styles, and cultural backgrounds. Each stone offers a unique combination of physical and symbolic qualities. Peridot, with its vivid green color and outer-space origins, stands out as both affordable and visually striking. Spinel is gaining modern popularity for its wide range of colors and durability, making it a versatile and practical gemstone for contemporary jewelry. Sardonyx, with its long history in cameo artistry and protective symbolism, remains a classic choice for those who appreciate craftsmanship and heritage.
Together, these three birthstones reflect not only the natural beauty of the Earth and beyond but also the evolving tastes and technologies of gemology. Whether selected for personal use, gift-giving, or historical appreciation, the August birthstones offer rich opportunities for exploration and expression.