August is unique among the calendar months in offering three distinct gemstones as its birthstones: peridot, spinel, and sardonyx. This trio provides individuals born in this summer month with a remarkable spectrum of colors, from the vibrant green of peridot to the fiery reds and blues of spinel and the striking banding of sardonyx. The existence of multiple birthstones for August reflects the evolution of gemological tradition and the modern desire for personal choice and variety. This article delves into the geological origins, historical significance, gemological properties, and cultural lore of these three captivating stones, drawing upon authoritative sources to provide a comprehensive guide for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
The tradition of birthstones is a long and complex one, with roots that can be traced to the biblical breastplate of the High Priest of Israel, which was said to be adorned with twelve gemstones representing the twelve tribes. Over centuries, these stones became associated with zodiac signs and eventually calendar months. The modern birthstone chart, as we know it, was standardized in the United States by the National Association of Jewelers (now Jewelers of America). The list for August has seen significant updates, reflecting changing tastes and the discovery of new gem sources.
Peridot, often called the "evening emerald" due to its glowing green hue, has a history dating back to ancient Egypt, where it was mined on the island of Zabargad in the Red Sea. The ancient Egyptians prized it for its protective qualities and believed it could ward off evil spirits. It was also a favorite of pirates, who thought it held the power to navigate storms. For centuries, peridot was often confused with emerald, but its distinct olive-green color, caused by its iron content, sets it apart. Its designation as a modern birthstone for August is well-established.
Spinel has a storied past, often masquerading as more famous gems. Some of history's most renowned "rubies," including the Black Prince's Ruby and the Timur Ruby in the British Crown Jewels, are actually red spinels. For centuries, spinel was not recognized as a distinct mineral species but was grouped with ruby and sapphire. It wasn't until the late 18th century that spinel was properly identified. Its addition to the August birthstone list is a relatively modern development, championed by the Jewelers of America to provide more color options for those born in August. Sources note that spinel's popularity is growing, and being named a birthstone has done more for its recognition than millions in advertising.
Sardonyx, a banded variety of chalcedony, has been used in jewelry for at least 2,000 years. It was particularly popular in ancient Rome and Greece for creating cameos and intaglios, where its layered structure was ideal for carving intricate designs. Sardonyx is a traditional birthstone for August, representing strength and protection. Its historical use in signet rings and amulets speaks to its enduring appeal as a material for both decorative and symbolic purposes. The inclusion of sardonyx alongside peridot and spinel on the modern chart offers a link to this ancient artistic tradition.
Geological Formation and Sources
Understanding where these gemstones come from enhances appreciation for their beauty and rarity. Each of the August birthstones forms under different geological conditions, leading to their unique characteristics.
Peridot is one of the few gemstones formed in the mantle, the layer of the Earth beneath the crust. It is brought to the surface by volcanic activity. Its primary chemical component is magnesium iron silicate, and its distinctive green color is due to the presence of iron. While peridot can be found in various locations, the most famous historical source is the island of Zabargad in the Red Sea, which supplied the ancient Egyptians. Modern sources include Arizona in the United States, as well as Pakistan and Myanmar. The gem is also found in some meteorites, a rare occurrence that adds to its mystique.
Spinel forms in metamorphic rocks and alluvial deposits. It is a magnesium aluminum oxide, and its color variety is due to trace elements like chromium (for red), iron (for blue or black), and vanadium. Major sources of spinel include Myanmar (Burma), Sri Lanka, and Thailand. Myanmar is particularly renowned for producing high-quality red and blue spinels. The gem's formation often occurs in limestone host rocks, where it can be found alongside other gems like ruby and sapphire. Its durability and wide color range make it a versatile and valuable gemstone.
Sardonyx is a variety of chalcedony, which is a microcrystalline form of quartz. It forms in volcanic or sedimentary rocks, where silica-rich solutions deposit layers of chalcedony, creating the characteristic bands of color. The bands are typically combinations of white, black, orange, red, or brown. Sardonyx is found in many parts of the world, including India, Germany, Brazil, and the United States. Its formation is relatively common, which contributes to its accessibility and use in a variety of jewelry forms, from beads to cameos.
Gemological Properties
The physical and optical properties of a gemstone determine its durability, brilliance, and suitability for jewelry. The three August birthstones have distinct profiles in this regard.
Peridot is a member of the olivine mineral group. It has a Mohs hardness of 6.5 to 7, making it reasonably durable but susceptible to scratches if worn daily in rings or bracelets without proper care. Its crystal structure is orthorhombic, and it exhibits a vitreous (glass-like) luster. Peridot typically has good clarity, with inclusions being common but often not affecting its beauty. It is pleochroic, meaning it can show different shades of green when viewed from different crystal directions. The most valued peridot colors are a rich, saturated olive green without brownish tints.
Spinel is a magnesium aluminum oxide with a cubic crystal system. It has a Mohs hardness of 8, which is exceptionally durable and suitable for all types of jewelry, including rings that will see daily wear. Its toughness is also excellent, meaning it can withstand impact without breaking. Spinel is isotropic, meaning it shows the same optical properties in all directions, and it has a high refractive index, contributing to its brilliance. It occurs in every color of the spectrum, with red (resembling ruby) and blue (resembling sapphire) being particularly prized. Clarity is generally good, with few inclusions.
Sardonyx is a cryptocrystalline quartz, with a Mohs hardness of 6.5 to 7, similar to peridot. It is relatively tough but can be scratched by harder materials. Its structure is microcrystalline, and it is typically cut as a cabochon or used for carving to highlight its banding. Sardonyx is opaque to translucent, and its value often depends on the sharpness and contrast of its bands. It is not known for exceptional brilliance but is valued for its unique patterns and historical significance.
The following table summarizes the key gemological properties of the August birthstones based on the provided sources:
| Gemstone | Chemical Composition | Mohs Hardness | Crystal System | Typical Colors | Durability Rating |
|---|---|---|---|---|---|
| Peridot | Magnesium Iron Silicate (Mg,Fe)₂SiO₄ | 6.5 - 7 | Orthorhombic | Olive Green, Yellow-Green | Fair to Poor |
| Spinel | Magnesium Aluminum Oxide MgAl₂O₄ | 8 | Cubic | Red, Blue, Pink, Black, etc. | Very Good |
| Sardonyx | Silicon Dioxide (Quartz) SiO₂ | 6.5 - 7 | Microcrystalline | Banded White, Black, Orange, Brown | Good |
Note: Durability ratings are based on the classifications provided in the sources, which consider hardness, toughness, and cleavage.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, gemstones have long been attributed with symbolic meanings and metaphysical powers. These beliefs, while not scientifically proven, form an important part of the cultural heritage surrounding birthstones.
Peridot is often associated with protection, healing, and prosperity. Ancient cultures believed it could ward off evil spirits and nightmares. It is sometimes called the "stone of the sun," thought to bring warmth and vitality to the wearer. In modern crystal healing, peridot is said to promote emotional balance, reduce stress, and encourage personal growth. Its vibrant green color is linked to renewal and nature, making it a symbol of new beginnings.
Spinel, with its wide array of colors, carries diverse meanings. Red spinel has historically been associated with passion, energy, and vitality, often confused with the symbolic power of ruby. Blue spinel is linked to calm, wisdom, and communication. Spinel is also believed to revitalize and rejuvenate, helping to overcome lethargy and stimulate the wearer's energy. Its durability is metaphorically linked to resilience and strength of character.
Sardonyx has been a talisman for strength, courage, and protection since ancient times. Roman soldiers wore sardonyx amulets into battle, believing it would grant them bravery and shield them from harm. As a stone of communication, it was thought to enhance eloquence and persuasive speech. The layered bands of sardonyx symbolize the integration of different aspects of the self, promoting stability and grounding. Its historical use in cameos and signet rings underscores its association with legacy and personal identity.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of gemstone jewelry. The August birthstones have different care requirements based on their physical properties.
Peridot, with its hardness of 6.5 to 7, is moderately durable but can be scratched by harder materials. It is also sensitive to sudden temperature changes and harsh chemicals. To clean peridot, use warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaners, as the vibrations and heat can cause damage. It is best to remove peridot jewelry during activities that could cause impact or exposure to chemicals, such as gardening or cleaning.
Spinel is highly durable, with a hardness of 8 and excellent toughness. It can be cleaned safely with warm, soapy water and a soft brush. Spinel is generally resistant to chemicals and heat, making it suitable for ultrasonic cleaners (though caution is always advised with any gemstone). Its durability means it can withstand daily wear with minimal risk of damage, making it an excellent choice for engagement rings and other frequently worn jewelry.
Sardonyx, like peridot, has a hardness of 6.5 to 7. It is relatively tough but can be scratched. As a variety of quartz, it is stable under normal conditions but should be protected from sharp blows and abrasive materials. Cleaning can be done with a soft brush and mild soapy water. Ultrasonic cleaners are generally safe for sardonyx, but steam cleaning is not recommended due to the potential for thermal shock. Given its use in cameos and carved pieces, extra care should be taken to avoid pressure on carved areas.
Conclusion
The three birthstones of August—peridot, spinel, and sardonyx—offer a diverse and fascinating palette for those born in this month. Peridot, with its ancient Egyptian heritage and vibrant green glow, symbolizes protection and renewal. Spinel, the durable and versatile gem often mistaken for ruby and sapphire, provides a spectrum of colors and exceptional toughness. Sardonyx, the banded chalcedony with a history spanning millennia, carries the legacy of ancient artistry and the symbolism of strength and communication. Together, they represent a rich tapestry of geological wonder, historical significance, and personal expression. Whether chosen for its beauty, durability, or symbolic meaning, each of these gemstones provides a unique connection to the natural world and the long tradition of birthstone lore. For individuals seeking a gemstone that reflects the warmth and vibrancy of summer, the August birthstones present an unparalleled selection.