The eighth month of the year is uniquely associated with three distinct gemstones, each offering a different palette, history, and set of characteristics. August’s birthstones—peridot, spinel, and sardonyx—provide a remarkable spectrum of color and durability, from the vibrant lime green of peridot to the fiery reds and blues of spinel and the banded earth tones of sardonyx. This trio of gems is celebrated not only for its aesthetic diversity but also for its historical significance, geological formation, and practical resilience in jewelry. As a month that bridges the warmth of summer and the transition to autumn, August’s birthstones embody a richness that appeals to collectors, jewelers, and those seeking personal meaning through gemstones.
This article explores the history, lore, geological origins, gemological properties, and care requirements of peridot, spinel, and sardonyx. It examines how each stone earned its place in the modern birthstone chart, the sources from which they are mined, and the symbolism that has been attached to them across cultures. By delving into the science and stories behind these gems, we provide a comprehensive resource for gemstone enthusiasts, jewelry buyers, and students of gemology interested in the unique offerings of August.
History and Lore
The tradition of assigning gemstones to calendar months has evolved over centuries, with the modern birthstone list largely standardized by the National Association of Jewelers (now Jewelers of America) in the early 20th century. For August, the original stone was peridot, a gem with a history that stretches back to ancient Egypt. However, in recent decades, spinel and sardonyx have been added as alternative or traditional options, expanding the choices for those born in this month.
Peridot is one of the oldest known gemstones, with historical records indicating its use in ancient Egypt. It was often called the “evening emerald” because its vibrant green color could be mistaken for emerald in certain lighting conditions. Egyptian miners extracted peridot from the island of Zabargad (also known as St. John’s Island) in the Red Sea, a source that was exploited as early as 1500 B.C. The gem was highly valued in ancient cultures, believed to ward off evil spirits and bring protection to its wearer. In medieval Europe, peridot was used to decorate church vessels and was associated with the Virgin Mary, earning it the nickname “Mary’s Stone.” Its historical significance is deeply rooted in both royalty and religion, making it a gem of enduring appeal.
Spinel has a more complex history, often overshadowed by its resemblance to more famous gems. For centuries, large red spinels were mistaken for rubies, and some of the most famous “rubies” in history, such as the Black Prince’s Ruby and the Timur Ruby in the British Crown Jewels, are actually spinels. The confusion persisted until the 18th century, when advances in gemology allowed for the differentiation of these stones based on their physical properties. Spinel’s journey to becoming an official August birthstone is recent; it was added to the modern birthstone list in 2016 by the American Gem Trade Association. This addition provided August-born individuals with a more colorful alternative to peridot, as spinel occurs in a wide range of hues, including red, blue, pink, and purple.
Sardonyx, a banded variety of chalcedony, has been used in jewelry and decorative arts for over 2,000 years. Its name derives from the Greek words “sard” (a reddish-brown color) and “onyx” (a black or white banded stone). Sardonyx was particularly prized in ancient Rome for creating cameos and intaglios, where its layered structure allowed artisans to carve intricate designs. The stone was believed to offer protection and courage, and Roman soldiers often wore amulets made from sardonyx. While not as commonly associated with August as peridot, sardonyx is included in some traditional birthstone lists, particularly those that emphasize historical and cultural significance over modern commercial preferences.
The evolution of the August birthstone list reflects a broader trend in which traditional stones are supplemented by modern alternatives. Peridot remains the primary birthstone for August, but the inclusion of spinel and sardonyx offers greater flexibility and choice. This diversification acknowledges the gemstone industry’s changing landscape, where new discoveries and cultural shifts influence what is considered “traditional.”
Geological Formation and Sources
Each of August’s birthstones forms under distinct geological conditions, resulting in unique chemical compositions and physical properties. Understanding how these gems are created provides insight into their rarity, value, and geographic origins.
Peridot is a variety of the mineral olivine, specifically the magnesium-rich endmember. It forms deep within the Earth’s mantle and is brought to the surface through volcanic activity. Peridot is one of the few gems that can be found in igneous rocks, particularly in basaltic lavas. The most famous source of peridot is the island of Zabargad in the Red Sea, which has been mined for millennia. Modern sources include Pakistan, where high-quality peridot is extracted from the Himalayan foothills, as well as Myanmar, China, and the United States (notably in Arizona and Hawaii). The gem’s color ranges from yellowish-green to olive green, with the most valued hues being a pure, vibrant green.
Spinel is a magnesium aluminum oxide (MgAl₂O₄) that forms in metamorphic rocks, particularly in marble and alluvial deposits. It is often found alongside other gems like ruby and sapphire, leading to historical confusion. The most significant sources of spinel include Myanmar (Burma), which produces the coveted red and blue varieties, as well as Sri Lanka, Vietnam, and Tanzania. The gem’s formation requires specific conditions of high temperature and pressure, making it a relatively rare mineral. In recent years, large deposits of spinel have been discovered in Madagascar, contributing to its increased availability in the market.
Sardonyx is a form of chalcedony, a microcrystalline variety of quartz. It forms in volcanic or sedimentary environments where silica-rich solutions deposit layers of color. The banding characteristic of sardonyx results from alternating layers of sard (brownish-red) and onyx (white or black). Major sources include India, Brazil, Germany, and the United States. Unlike peridot and spinel, sardonyx is relatively abundant and affordable, making it accessible for a wide range of jewelry applications. Its formation process is slow, often occurring in geodes or nodules, where the silica gel gradually solidifies into layered bands.
The geographic distribution of these gems highlights their diverse origins. Peridot’s volcanic roots tie it to active geological regions, while spinel’s metamorphic formation links it to mountain-building processes. Sardonyx, as a sedimentary deposit, reflects a more placid geological history. Together, these stones illustrate the Earth’s capacity to produce beauty through varied and complex processes.
Gemological Properties
The durability, appearance, and value of a gemstone are determined by its gemological properties, including hardness, color, clarity, and chemical composition. The following table summarizes the key properties of August’s birthstones, based on data from authoritative sources.
| Gemstone | Chemical Composition | Hardness (Mohs Scale) | Crystal System | Typical Colors | Notable Properties |
|---|---|---|---|---|---|
| Peridot | (Mg,Fe)₂SiO₄ | 6.5–7.0 | Orthorhombic | Yellowish-green to olive green | High birefringence; often found in volcanic rocks |
| Spinel | MgAl₂O₄ | 8.0 | Cubic | Red, blue, pink, purple, black | High durability; can mimic ruby and sapphire |
| Sardonyx | SiO₂ (microcrystalline) | 6.5–7.0 | Hexagonal | Banded brown, white, black, orange | Opaque; often cut into cabochons or cameos |
Peridot has a hardness of 6.5 to 7 on the Mohs scale, making it suitable for most jewelry but requiring care to avoid scratches from harder materials. Its refractive index is relatively low, but it exhibits strong birefringence, which can sometimes cause doubling of facets under magnification. Peridot is typically free of inclusions, but some stones may contain small fluid or mineral inclusions. The gem’s color is due to iron impurities, and the most prized specimens display a vivid green hue with minimal brownish undertones.
Spinel is one of the most durable gemstones, with a hardness of 8 on the Mohs scale and excellent toughness. Its cubic crystal system contributes to its high refractive index and brilliance, which can rival that of diamond. Spinel is often found with minimal inclusions, though some varieties may contain needle-like inclusions or zoning. The gem’s color is influenced by trace elements; for example, chromium produces red spinel, while iron and cobalt can create blue or pink shades. Its durability makes it an excellent choice for rings and other frequently worn jewelry.
Sardonyx, as a form of chalcedony, has a hardness of 6.5 to 7 and a specific gravity of 2.58–2.64. It is opaque and typically cut into cabochons, beads, or cameos to showcase its banding. The stone’s color patterns are natural and can vary widely, from subtle earth tones to high-contrast black-and-white designs. Sardonyx is not known for its brilliance, but its visual appeal lies in its layered structure and historical use in carved jewelry.
In terms of value, peridot and spinel can command high prices for fine specimens, especially those with exceptional color and clarity. Sardonyx is generally more affordable, though intricate carvings or large pieces can be valuable. All three stones are durable enough for everyday wear, though peridot and sardonyx require slightly more care than spinel due to their lower hardness.
Symbolism and Metaphysical Beliefs
Beyond their physical properties, gemstones have long been imbued with symbolic meaning and metaphysical beliefs. Each of August’s birthstones carries a legacy of symbolism that adds to its cultural significance.
Peridot is associated with strength, protection, and healing. In ancient Egypt, it was believed to ward off evil spirits and bring prosperity to its wearer. Medieval Europeans thought peridot could improve vision and promote emotional balance. Today, it is often linked to the heart chakra, symbolizing love and compassion. Peridot’s vibrant green color is also connected to nature, growth, and renewal, making it a popular choice for those seeking personal transformation.
Spinel has historically been a stone of immortality and rejuvenation. Its resemblance to ruby and sapphire led to it being mistaken for these “king of gems,” and it inherited some of their symbolic attributes. Red spinel is associated with passion and vitality, while blue spinel represents wisdom and clarity. In modern crystal healing, spinel is believed to energize the body and mind, promoting resilience and overcoming obstacles. Its durability is often interpreted as a metaphor for inner strength.
Sardonyx is traditionally linked to courage, protection, and happiness. In ancient Rome, soldiers wore sardonyx amulets to gain bravery in battle. The stone’s banded layers are thought to represent balance and harmony, making it a symbol of stability. Sardonyx is also associated with marital fidelity and long-term commitment, which is why it was often used in engagement rings and wedding jewelry in historical contexts.
These symbolic meanings, while not scientifically verified, contribute to the enduring appeal of these gemstones. They allow individuals to connect with their birthstone on a personal or spiritual level, enhancing the emotional value of the jewelry they wear.
Care and Cleaning
Proper maintenance is essential to preserve the beauty and longevity of gemstone jewelry. The care requirements for August’s birthstones vary based on their hardness, cleavage, and sensitivity to chemicals.
Peridot requires careful handling due to its moderate hardness and potential for cleavage. It should be cleaned with warm, soapy water and a soft brush, avoiding ultrasonic cleaners and steam, which can cause fractures. Peridot is sensitive to rapid temperature changes and should be stored separately from harder gems to prevent scratching. When worn regularly, it is best suited for pendants or earrings rather than rings, though it can be used in rings if placed in a protective setting.
Spinel is highly durable and can withstand more rigorous cleaning methods. It can be cleaned with warm soapy water, ultrasonic cleaners, and even steam, though caution is advised for stones with inclusions. Spinel’s hardness and lack of cleavage make it ideal for all types of jewelry, including rings and bracelets. It should be stored in a soft cloth or compartmentalized box to avoid contact with other gems.
Sardonyx, as an opaque stone, is relatively easy to care for. It can be cleaned with a soft cloth and mild soap, avoiding harsh chemicals that might damage its surface. Sardonyx is not prone to cracking but can be scratched by harder materials, so it should be stored separately. Its cabochon or carved surfaces are best preserved by avoiding abrasive cleaners or rough handling.
General advice for all three stones includes avoiding exposure to extreme heat, direct sunlight (which can fade peridot’s color over time), and harsh chemicals like bleach or ammonia. Regular inspections by a professional jeweler can help ensure settings are secure and stones are undamaged.
Conclusion
August’s birthstones—peridot, spinel, and sardonyx—offer a diverse and rich selection for those born in this month. From the ancient volcanic origins of peridot to the historically mistaken spinel and the artistically valued sardonyx, each gem carries a unique story and set of properties. Peridot’s vibrant green symbolizes protection and growth, spinel’s durability and color range provide versatility, and sardonyx’s banded patterns evoke history and craftsmanship. Together, they represent the geological and cultural wealth of the gemstone world, providing options that cater to different tastes, budgets, and symbolic preferences. Whether chosen for their beauty, durability, or meaning, these stones remain timeless symbols of August’s enduring legacy.