The month of August is uniquely distinguished in the world of gemology by offering not one, but three conventional and alternative birthstones: Peridot, Spinel, and Sardonyx. While many months rely on a single gem to represent those born within their days, August provides a triad of distinct options, each with its own geological history, symbolic meaning, and aesthetic appeal. This abundance allows individuals born in August to select a stone that best resonates with their personal style and the attributes they wish to embody. The modern list of August birthstones was officially recognized in 2016 when the American Gem Trade Association (AGTA) and the Jewelers of America (JA) added Spinel to the existing pair of Peridot and Sardonyx. This article explores the rich tapestry of history, lore, and gemological science behind these three remarkable gems.
Historical Significance and Lore
The history of August's birthstones is as layered as the gems themselves, spanning ancient civilizations, biblical references, and modern recognition.
Sardonyx: The Ancient Protector
Sardonyx holds the distinction of being the earliest recorded birthstone for August. Its use dates back thousands of years, deeply rooted in ancient history and religious texts. Sardonyx is mentioned multiple times in the Bible; it was counted among the foundation stones of Jerusalem and was set on the breastplate of Aaron, the High Priest. This stone, composed of alternating layers of sard and onyx, was highly valued for its distinctive banding. In ancient Rome, soldiers often wore Sardonyx amulets, believing the stone would protect them in battle and grant them courage. Its association with steadfastness and protection made it a popular choice for signet rings, as the contrasting bands could be carved to create striking cameos and intaglios.
Peridot: The Volcanic Emerald
Peridot, with its vibrant olive-green hue, has often been mistaken for emerald throughout history. It is sometimes referred to as the "evening emerald" due to its ability to retain its color under artificial light. Ancient Egyptians mined Peridot on the island of Zabargad (now St. John's Island) in the Red Sea as early as 1500 B.C. The gem was so revered that they called it the "gem of the sun." Folklore suggests that the green crystals found in volcanic ashes were actually the tears of the volcano goddess Pele, linking the stone to powerful natural forces. When set in gold, Peridot was believed to ward off nightmares and protect the wearer from evil spirits. Its symbolism has evolved to represent strength, renewal, and vitality.
Spinel: The Great Imposter
Spinel entered the list of August birthstones much more recently, yet its history is equally fascinating. For centuries, Spinel was the "great imposter," frequently confused with ruby. Many of the world's most famous "rubies," such as the Black Prince's Ruby and the Timur Ruby in the British Crown Jewels, were later discovered to be red Spinels. These magnificent stones were mined in the historical region of Badakhshan (modern-day Tajikistan and Afghanistan). While it was long overshadowed by its ruby counterpart, Spinel is now celebrated for its own brilliance and range of colors, finally stepping out of the shadow of its more famous relative to claim its place as a distinct and valuable gemstone.
Geological Formation and Mining Locations
Understanding the origins of these stones reveals the diverse geological processes that create them.
Sardonyx Formation and Sources
Sardonyx is a variety of chalcedony, which itself is a microcrystalline form of quartz (silicon dioxide). It is classified as a banded agate, formed in volcanic rock cavities where silica-rich solutions deposit layers over time. The distinctive bands are created by the presence of iron oxides, which color the layers of sard (ranging from reddish-brown to reddish-yellow) and onyx (typically black or white). Major sources for Sardonyx include India, Brazil, Germany, and the United States. Its relative abundance and ease of cutting make it an accessible and affordable option for jewelry.
Peridot Formation and Sources
Peridot is unique among the gemstones as it is formed deep within the Earth's mantle, rather than in the crust. It is brought to the surface through volcanic activity. This gem is the gemological name for the mineral olivine (chemical formula (Mg, Fe)₂SiO₄). The most famous ancient source was the island of Zabargad in the Red Sea. Today, significant deposits are found in Pakistan, Arizona (USA), Myanmar, and Norway. The color of Peridot is determined by its iron content, with the finest stones exhibiting a rich, vibrant olive green with a slight golden tint.
Spinel Formation and Sources
Spinel (chemical formula MgAl₂O₄) forms under similar metamorphic conditions as ruby and sapphire, often found in the same marble deposits. This geological proximity is the primary reason for its historical confusion with corundum. Spinel crystals can also form in alluvial deposits, washed down from their original host rock. Historically, the most prized red Spinels came from the Badakhshan region of Central Asia. Today, significant sources include Vietnam, Tajikistan, Sri Lanka, and Tanzania.
Gemological Properties
Each of the August birthstones possesses a unique set of physical and chemical characteristics that define its durability, appearance, and value.
| Gemstone | Chemical Composition | Hardness (Mohs) | Crystal System | Common Colors |
|---|---|---|---|---|
| Peridot | (Mg, Fe)₂SiO₄ | 6.5 – 7 | Orthorhombic | Olive green, yellowish-green |
| Spinel | MgAl₂O₄ | 8 | Cubic | Red, pink, blue, violet, black |
| Sardonyx | SiO₂ (Chalcedony) | 6.5 – 7 | Trigonal (micro) | Banded reddish-brown and white/black |
Peridot Properties
Peridot rates a 6.5 to 7 on the Mohs scale of hardness, making it suitable for most jewelry, though it requires some care to avoid scratches and chipping. It is one of the few gemstones that occurs in only one color: a distinct yellowish-green to olive green. The presence of iron gives it this signature hue. Peridot has good toughness but can be brittle due to some internal weaknesses. It is typically eye-clean, meaning inclusions are not usually visible to the naked eye.
Spinel Properties
Spinel is a much harder and more durable gemstone, rating an 8 on the Mohs scale. This makes it excellent for all types of jewelry, including daily-wear rings. It possesses excellent clarity and a high refractive index, giving it a brilliance comparable to that of a ruby or sapphire. Spinel is celebrated for its wide range of colors, including vibrant reds, hot pinks, deep blues, and even blacks. The red and pink varieties are the most popular and are often compared to ruby and pink sapphire, respectively.
Sardonyx Properties
As a variety of chalcedony, Sardonyx has a hardness of 6.5 to 7 and a trigonal crystal system. Its defining characteristic is its banding. The alternating layers of sard and onyx create a striking contrast, often appearing as reddish-brown or orange bands alongside white or black bands. This layered structure makes it ideal for carving, which is why it has been used for cameos and intaglios for centuries.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, these stones have been attributed with various symbolic meanings and metaphysical powers throughout history.
- Peridot is widely associated with strength and renewal. Its connection to the sun and volcanic origins lends it an aura of vitality and life force. It is believed to bring good luck, peace, and health to its wearer. In modern crystal healing, Peridot is often used to promote growth, open the heart to new experiences, and alleviate feelings of jealousy and resentment.
- Spinel, particularly the red varieties, has long been associated with vitality and passion, much like the ruby it often resembles. It is thought to inspire hope, joy, and resilience. Blue spinel is associated with calm and tranquility, while pink spinel is linked to love and compassion. As a stone that was often mistaken for a ruby, it carries the symbolism of being a "hidden treasure" or a source of overlooked potential.
- Sardonyx is the stone of courage and protection. Its historical use by Roman soldiers and its biblical significance have cemented its reputation as a guardian stone. It is believed to promote discipline, integrity, and steadfastness. Sardonyx is also associated with happiness and clear communication, making it a popular choice for those seeking stability in their relationships and personal lives.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones. Their varying hardness and structural properties dictate the best methods for cleaning and storage.
Caring for Peridot
Due to its moderate hardness (6.5-7) and potential for brittleness, Peridot should be protected from hard knocks and extreme temperature changes. To clean it, use warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaners, as the heat and vibrations can cause damage. Store Peridot separately from harder stones to prevent scratching.
Caring for Spinel
Spinel is one of the more durable gemstones, with a hardness of 8 and good toughness. It is relatively easy to care for. It can be safely cleaned using warm, soapy water and a soft brush. It is also generally safe to use an ultrasonic cleaner, though caution is advised if the stone has any fractures. Spinel is stable under light and is not affected by most chemicals.
Caring for Sardonyx
As a member of the quartz family, Sardonyx is reasonably durable but can be scratched by harder materials. Standard cleaning with warm, soapy water and a soft cloth is sufficient. It is best to avoid harsh chemicals and extreme heat. Given its use in carved jewelry, pay special attention to cleaning crevices and grooves where dirt can accumulate.
Conclusion
August's birthstones—Peridot, Spinel, and Sardonyx—offer a remarkable diversity of color, history, and meaning. From the ancient, banded protection of Sardonyx to the volcanic, sun-kissed glow of Peridot and the brilliant, long-misidentified allure of Spinel, each gem provides a unique narrative. This trio ensures that anyone born in the eighth month of the year has a wealth of choice, whether they are drawn to the deep historical roots of Sardonyx, the vibrant green of Peridot, or the dazzling array of colors offered by Spinel. Together, they represent strength, protection, and vitality, making them enduring symbols of the late summer season.