August is unique in the world of birthstones, offering two distinct and vibrant choices: peridot and spinel. While peridot has long been recognized as the primary birthstone for this summer month, spinel has gained significant prominence as a modern alternative, celebrated for its exceptional durability and spectrum of colors. Both gemstones carry their own rich histories, geological origins, and symbolic meanings, providing August-born individuals with a diverse palette of options for personal jewelry. This article will explore the characteristics, lore, and practical considerations for both peridot and spinel, drawing on historical records and gemological data to provide a comprehensive overview for enthusiasts and collectors alike.
Historical Roots and the Path to Birthstone Status
The tradition of assigning specific gemstones to months of the year has ancient origins, tracing back at least two millennia. The practice is often linked to the writings of Josephus in the first century of the common era and St. Jerome in the early fifth century, who described the twelve stones on the High Priest's breastplate in the Book of Exodus as being associated with the twelve tribes of Israel and, by later interpretation, the twelve months of the year and the zodiac signs. This foundational concept evolved over centuries, with the modern list of birthstones largely solidifying in the 20th century.
Peridot has a storied history, with records of its use dating back to ancient Egypt. The gemstone was known to the Egyptians as "the gem of the sun" and was believed to have protective properties. It was mined on the island of Zabargad (now St. John's Island) in the Red Sea, a source that provided some of the finest peridot crystals in antiquity. The gem's vibrant green hue, which comes from iron in its chemical composition, was highly prized and often mistaken for emeralds. Historical accounts, such as those documented by gemologist George Frederick Kunz, note that peridot was used in the jewelry of royalty and clergy throughout history, and it was even incorporated into church treasures.
Spinel's history is equally fascinating, though it is often overshadowed by its more famous corundum cousins, ruby and sapphire. For centuries, many large red spinels were mistaken for rubies. The most famous example is the "Black Prince's Ruby," a 170-carat red spinel that is part of the British Crown Jewels, which was long believed to be a ruby. Similarly, the "Timur Ruby," another large red spinel, was also misidentified. This confusion was common because spinel occurs in similar colors and can be found in the same geographic regions as ruby and sapphire. It wasn't until the 18th century that spinel was formally recognized as a distinct mineral species. Its inclusion as a modern birthstone for August, as noted in contemporary sources, is a relatively recent development, intended to provide an alternative to peridot and to celebrate spinel's own merits.
Geological Formation and Sources
Peridot is a gem-quality variety of the mineral olivine, a magnesium iron silicate with the chemical formula (Mg,Fe)₂SiO₄. Its formation is unique among gemstones, as it is created in the Earth's mantle and brought to the surface by volcanic activity. This process can sometimes result in large, high-quality crystals. Peridot is found in a variety of geological settings. In addition to the historic Egyptian deposits, significant sources include the San Carlos Apache Reservation in Arizona, which produces a large percentage of the world's supply of peridot. Other notable locations include Pakistan, Myanmar, and Australia. The gem's color can range from a light yellow-green to a deep olive, with the most valued hues being a vibrant, pure green with no brownish tints.
Spinel is a magnesium aluminum oxide (MgAl₂O₄) and forms in the metamorphic rock of the Earth's crust, often in association with marble and other magnesium-rich rocks. It can also be found in alluvial deposits, where it has been weathered from its host rock and transported by water. Spinel's formation conditions are similar to those for ruby and sapphire, which explains why it is often found in the same regions. Major sources for spinel include Myanmar (Burma), which is famous for its vibrant red and pink spinels; Sri Lanka, known for its blue, violet, and pink stones; and Tajikistan, which produces a range of colors. Other sources include Vietnam, Tanzania, and Afghanistan. The gem's ability to form in a wide array of colors is a direct result of trace elements like iron, cobalt, and chromium that can be incorporated into its crystal structure during formation.
Gemological Properties: A Comparative Analysis
Understanding the physical and chemical properties of these gemstones is crucial for both identification and practical use in jewelry. The following table provides a side-by-side comparison of key gemological characteristics for peridot and spinel, based on information from authoritative gemological sources.
| Property | Peridot | Spinel |
|---|---|---|
| Chemical Formula | (Mg,Fe)₂SiO₄ | MgAl₂O₄ |
| Crystal System | Orthorhombic | Cubic |
| Hardness (Mohs Scale) | 6.5 - 7 | 8 |
| Refractive Index | 1.64 - 1.70 | 1.712 - 1.762 |
| Specific Gravity | 3.27 - 4.37 | 3.57 - 4.26 |
| Common Colors | Olive green, yellow-green | Red, blue, pink, purple, black, white |
| Durability | Fair to Good | Excellent |
As the table indicates, spinel has a significant advantage in hardness and overall durability. With a Mohs hardness of 8, spinel is highly resistant to scratching and abrasion, making it an excellent choice for jewelry that is worn daily, such as rings and bracelets. Peridot, with a hardness of 6.5 to 7, is more susceptible to scratches and requires careful handling and protective settings. Both stones are relatively free of inclusions in high-quality specimens, but peridot can sometimes contain small, needle-like inclusions known as "lily pads," which are a characteristic feature of the gem.
Color is a primary factor in the value of both stones. For peridot, the most prized color is a rich, grassy green, with the finest examples coming from the deep red volcanic soils of Pakistan and Myanmar. Spinel's value is heavily influenced by color, with red and blue varieties being the most sought after. Red spinel, colored by chromium, can rival the finest ruby in its saturation, while blue spinel, often colored by iron or cobalt, is a popular alternative to sapphire. The gem's exceptional clarity and vitreous luster further enhance its appeal.
Symbolism and Metaphysical Beliefs
The symbolic meanings attributed to these gemstones are as varied as their colors. Peridot, with its association with the sun in ancient Egypt, has long been linked to light, warmth, and protection. It was believed to ward off evil spirits and bring good fortune and health to its wearer. In modern crystal healing and metaphysical practices, peridot is often associated with abundance, prosperity, and emotional balance. It is sometimes called the "stone of compassion" and is believed to help heal heartache and open the heart to new relationships.
Spinel, while not as steeped in ancient lore as peridot, has accumulated its own set of beliefs. Historically, its misidentification with ruby and sapphire led to it inheriting some of the symbolic properties of those stones, such as passion, power, and wisdom. In contemporary metaphysical circles, spinel is often considered a stone of revitalization and renewal. It is believed to stimulate all chakras, remove energy blockages, and promote physical and emotional resilience. Different colors of spinel are associated with different properties; for example, red spinel is linked to passion and courage, while blue spinel is connected to communication and calm.
It is important to note that these metaphysical beliefs, while widely popular, are not based on scientific evidence and are considered by the gemological community to be part of cultural and spiritual tradition rather than gemological fact. Their value lies in the personal meaning and intention that individuals ascribe to them.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone. Given their differing physical properties, peridot and spinel require slightly different handling.
Peridot Care: Due to its moderate hardness (6.5-7) and lack of cleavage, peridot is relatively durable but not impervious to damage. It can be scratched by substances with a higher hardness, such as quartz (hardness 7). To clean peridot, use warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaners, as the heat and vibrations can potentially damage the stone or its setting. It is also advisable to remove peridot jewelry before engaging in activities that could subject it to hard blows or abrasion, such as gardening, heavy lifting, or sports.
Spinel Care: Spinel's excellent durability (hardness 8) makes it one of the most resilient gemstones for jewelry. It is resistant to most chemicals and can withstand the rigors of daily wear. Cleaning spinel is straightforward; it can be safely cleaned with warm, soapy water and a soft brush. While spinel is more tolerant of ultrasonic cleaners than many other gemstones, it is always best to consult with a professional jeweler before using such methods, especially if the stone is set in a delicate or older piece of jewelry. Its toughness and lack of cleavage mean it is unlikely to chip or crack from normal wear, making it an ideal choice for engagement rings and other high-impact jewelry.
Conclusion
Peridot and spinel represent two exceptional choices for the August birthstone. Peridot offers a long and storied history, a vibrant green color derived from its unique formation in the Earth's mantle, and a symbolic connection to light and abundance. Spinel, in contrast, provides a modern alternative with an impressive range of colors, exceptional durability, and a fascinating history of being mistaken for more famous gems. Both stones possess distinct gemological properties and care requirements, allowing individuals to select a gem that aligns with their lifestyle and aesthetic preferences. Whether drawn to the ancient allure of peridot or the resilient beauty of spinel, those born in August are fortunate to have two of the gem world's most captivating and durable stones to call their own.