August is a month uniquely distinguished in the world of gemology, not for one, but for three official birthstones: Peridot, Sardonyx, and Spinel. Each of these gemstones carries its own rich history, cultural significance, and geological allure. From the fiery brilliance of peridot to the intricate banding of sardonyx and the regal allure of spinel, August’s birthstones offer a captivating palette of colors and stories.
This article explores the scientific properties, historical roots, cultural symbolism, and modern appeal of these three gemstones. Drawing from a variety of authoritative and historical sources, we will uncover how these stones have evolved from ancient relics to contemporary treasures, and how they continue to enchant gemstone lovers and jewelry enthusiasts alike.
History and Lore
Sardonyx: The Ancient August Birthstone
Sardonyx is the oldest of the August birthstones, with a history stretching back over 4,000 years. It is a banded chalcedony, a type of quartz, composed of sard (a reddish-brown to orange variety of chalcedony) and onyx (a black or white banded chalcedony). The name “sardonyx” is derived from the combination of the two components—sard and onyx—reflecting the stone’s characteristic alternating layers of color.
Historically, sardonyx was revered in ancient Egypt, Greece, and Rome. It was commonly used to carve cameos, signet rings, and other ornamental objects, often associated with protection, strength, and nobility. The stone’s vivid banding made it a favorite for intaglio and cameo work, where the contrasting layers could be used to create intricate designs.
By the 19th century, sardonyx had already established itself as the original birthstone for August, appearing in the catalogs of jewelers and gemologists of the time. It was valued not only for its aesthetic appeal but also for its durability, making it a practical choice for everyday jewelry.
Peridot: The "Evening Emerald"
Peridot, the green gemstone formed from the mineral olivine, has a more recent but equally fascinating history. Known as the “gem of the sun,” peridot was once believed to absorb the sun’s rays during the day and emit a soft glow at night. This phenomenon, however, is more likely due to light reflection rather than any intrinsic luminescence.
Peridot was historically misidentified as other gems such as topaz and emerald, especially in ancient times. The Red Sea island of Topazios, which gave its name to the gemstone topaz, was actually a source of peridot. Some of the emeralds in the Shrine of the Three Holy Kings in Cologne Cathedral are now believed to be peridot, highlighting the confusion between the two stones in early gemology.
Peridot was officially recognized as an August birthstone in 1912 by the National Association of Jewelers (now Jewelers of America). This decision reflected both the gem’s availability and its popularity in the jewelry trade. Peridot’s vibrant green color, ranging from lime to olive, made it a standout gem in the early 20th century, and it has remained a favorite ever since.
Spinel: The Modern Addition to the August Birthstone Lineup
Spinel, the most recent addition to the August birthstone list, was officially included in 2016 by the Jewelers of America and the American Gem Trade Association. This decision marked a growing appreciation for spinel, a gemstone often mistaken for ruby or sapphire due to its similar colors and brilliance.
Spinel has been used in royal collections for centuries, including in the Crown Jewels of the United Kingdom, where it was often misidentified as ruby. The red spinel in the Crown of the United Kingdom, for instance, was once thought to be a ruby. Spinel’s rich reds, pinks, and oranges make it a striking and versatile gemstone, and its inclusion in the August birthstone lineup reflects both its beauty and its historical significance.
The addition of spinel to the August birthstone list reflects a broader trend in the jewelry industry to expand the diversity of gemstone choices and to educate consumers about lesser-known but equally valuable stones.
Geological Formation and Sources
Sardonyx: A Banded Chalcedony
Sardonyx is a type of chalcedony, a microcrystalline quartz composed of silica (SiO₂). Its banded appearance is due to alternating layers of sard and onyx, which form in sedimentary environments, often in the cavities of volcanic rock.
The primary sources of sardonyx today include India, where the stone is known for its sharp contrast between the red sard and the white or black onyx. Other notable sources include Brazil, Madagascar, Germany, and the United States, where sardonyx is mined from quarries in states like Arizona and New Mexico.
Sardonyx is relatively soft compared to other gemstones, with a Mohs hardness of 6 to 7, and is best suited for low-wear jewelry such as pendants or brooches. Its durability and affordability make it a popular choice for engraving and cameo work.
Peridot: Formed in Fire and Meteorites
Peridot is the olivine mineral in its gem-quality form and is one of the few gemstones that can be found in meteorites. Its formation is tied to extreme geological conditions, including high pressure and temperature, and it is often found in hardened lava flows and igneous rocks.
The chemical composition of peridot is (Mg,Fe)₂SiO₄, and its green color is due to the presence of iron (Fe). The intensity of the green color varies depending on the iron content, with higher iron content producing deeper, more vibrant greens.
Peridot is mined in various locations around the world, including the U.S. (Arizona), Egypt, Pakistan, Australia, and Brazil. The island of Zabargad in the Red Sea, historically known as Topazios, is one of the most famous sources of peridot.
Peridot has a Mohs hardness of 6.5 to 7, making it suitable for everyday wear, though it should be handled with care to avoid scratching or chipping.
Spinel: A Diverse and Durable Gem
Spinel is a oxide mineral with the chemical formula MgAl₂O₄, and it occurs in a wide range of colors, including red, pink, orange, blue, green, and black. The red and pink varieties are the most commonly associated with August’s birthstone lineup.
Spinel forms in igneous rocks, particularly garnet-bearing mafic rocks, and is also found in metamorphic environments. It is harder than peridot and sardonyx, with a Mohs hardness of 8, making it more durable and suitable for a wider range of jewelry applications.
The primary sources of spinel include Sri Lanka, Myanmar (Burma), Vietnam, and Tanzania. The Jewelers of America added spinel to the August birthstone list in 2016 to recognize its beauty and historical significance, especially in royal and historical jewelry collections.
Gemological Properties
Sardonyx
| Property | Value |
|---|---|
| Mineral | Chalcedony (a type of quartz) |
| Chemical Formula | SiO₂ |
| Color | Bands of brownish red (sard) and white or black (onyx) |
| Refractive Index | 1.53–1.54 |
| Birefringence | 0.017 |
| Specific Gravity | 2.60–2.64 |
| Mohs Hardness | 6–7 |
| Cleavage | None |
| Luster | Waxy to vitreous |
| Transparency | Translucent to opaque |
Peridot
| Property | Value |
|---|---|
| Mineral | Olivine |
| Chemical Formula | (Mg,Fe)₂SiO₄ |
| Color | Yellowish green to greenish yellow |
| Refractive Index | 1.65–1.69 |
| Birefringence | 0.035–0.038 |
| Specific Gravity | 3.34 |
| Mohs Hardness | 6.5–7 |
| Cleavage | Good in two directions |
| Luster | Vitreous |
| Transparency | Transparent to translucent |
Spinel
| Property | Value |
|---|---|
| Mineral | Spinel |
| Chemical Formula | MgAl₂O₄ |
| Color | Red, pink, orange, blue, green, black |
| Refractive Index | 1.718 |
| Birefringence | 0.005–0.010 |
| Specific Gravity | 3.6–4.0 |
| Mohs Hardness | 8 |
| Cleavage | None |
| Luster | Vitreous |
| Transparency | Transparent to translucent |
Symbolism and Metaphysical Beliefs
Sardonyx
In ancient times, sardonyx was believed to offer protection against harm and envy, and was often worn by soldiers and warriors for courage and strength. It was also associated with truth, loyalty, and justice, making it a favored gemstone among rulers and nobility.
In modern times, sardonyx is believed to enhance willpower and mental clarity, and to help overcome self-doubt and fear. It is also used in feng shui and crystal healing practices to balance emotions and promote harmony.
Peridot
Peridot is known as the “gem of the sun”, and in ancient Egypt, it was believed to bring light and protection to its wearer. It was also used to ward off nightmares and evil spirits, and was often placed under pillows or in homes for protection.
In modern metaphysical practices, peridot is associated with positive energy, abundance, and emotional healing. It is believed to stimulate the heart and solar plexus chakras, helping to release negative emotions and attract new opportunities.
Spinel
Spinel, though less commonly attributed with metaphysical properties, has been historically linked to passion, courage, and vitality. In medieval Europe, it was believed to bring good fortune and protect against illness.
In modern crystal healing, spinel is associated with motivation, energy, and emotional balance. It is also believed to enhance communication and strengthen relationships, making it a popular choice for love and friendship jewelry.
Care and Cleaning
Sardonyx
Sardonyx is relatively durable, but due to its lower hardness, it should be cleaned gently. Use a soft cloth and mild soap and water. Avoid ultrasonic or steam cleaners, as they may cause damage to the stone’s surface or alter its color.
Store sardonyx away from harder gemstones to prevent scratching, and avoid exposure to harsh chemicals or prolonged sunlight, which may fade its colors over time.
Peridot
Peridot has a good hardness, but it is susceptible to scratches and can be damaged by heat or sudden temperature changes. Clean peridot with warm soapy water and a soft brush, and avoid ultrasonic cleaners, especially if the stone has any inclusions or fractures.
Store peridot in a soft pouch or separate compartment to prevent contact with other gemstones, and avoid exposure to extreme temperatures or direct sunlight for long periods.
Spinel
Spinel is one of the hardest of the August birthstones, with a Mohs hardness of 8, making it very durable and suitable for daily wear. It can be cleaned with ultrasonic or steam cleaners, though always follow the manufacturer’s instructions.
Store spinel in a secure, padded container to prevent chipping or scratching, and avoid exposure to harsh chemicals, which may damage the surface or alter its color.
Conclusion
August’s birthstones—Peridot, Sardonyx, and Spinel—offer a rich tapestry of history, beauty, and symbolism. From the ancient banding of sardonyx to the sunlit vibrancy of peridot, and the regal allure of spinel, these gemstones reflect the diversity and depth of gemological treasures.
Whether you are an enthusiast of gemology, a jewelry buyer, or simply someone born in August, these stones offer more than just beauty—they carry the stories of civilizations, the science of the Earth, and the enduring power of natural wonder.
In a world that increasingly values individuality and authenticity, the three August birthstones stand as a testament to the richness of gemstone history and the endless possibilities of jewelry design and personal expression.