For those born in the month of August, the choice of birthstone is not a single gem but a vibrant pair: the luminous green peridot and the brilliant, often overlooked spinel. This duality offers a fascinating study in gemology, contrasting two distinct minerals that share a common birth month. The August birthstones represent a spectrum of color, from peridot’s olive to neon green to spinel’s fiery reds and vivid pinks. Their value is determined by a complex interplay of rarity, origin, and market demand, making them accessible to a wide range of collectors and jewelry enthusiasts. This article delves into the geological origins, gemological properties, historical significance, and market value of these two remarkable gems, providing a detailed resource for understanding the science and allure behind August's birthstones.
History and Lore
The history of August's birthstones is a tale of two gems with distinct paths to recognition. Peridot, with its rich green hue, has been prized for millennia. Its origins are ancient, with some of the most significant historical sources being the ancient Egyptians. The gemstone was known to them as the "gem of the sun," and it was believed to offer protection from nightmares and evil spirits. A notable historical source for peridot was the island of Zabargad (St. John's Island) in the Red Sea, which produced peridots for centuries. The gem's association with light and the sun is a recurring theme in its lore.
Spinel’s history is more complex, largely due to its frequent confusion with other red gemstones, most notably ruby. For centuries, some of the world's most famous "rubies" were, in fact, spinels. The most famous example is the Black Prince's Ruby, a massive red spinel that has been part of the British Crown Jewels since the 14th century. Similarly, the Timur Ruby, another large red spinel, has a long and storied history in Asian and European collections. This historical misidentification has often overshadowed spinel's own identity. However, in the late 20th century, spinel began to gain recognition as a gemstone in its own right, valued for its exceptional brilliance and durability. The modern birthstone lists, first established by the National Association of Jewelers in 1912 and later updated, have included both peridot and spinel as August birthstones, with spinel officially added as an alternative in 2016, acknowledging its growing popularity and unique merits.
Geological Formation and Sources
The two August birthstones originate from vastly different geological environments, which directly influences their availability and characteristics.
Peridot is a variety of the mineral olivine, with the chemical formula (Mg,Fe)₂SiO₄. Its formation is primarily linked to the Earth's mantle. Peridot crystals are brought to the surface through volcanic activity, often found in basaltic lava flows. This process is responsible for some of the largest and most famous peridot deposits. Historically, the most renowned source was the island of Zabargad in the Red Sea. In modern times, significant deposits are found in Arizona, USA, where large peridots are mined from basaltic rock. Other notable sources include Pakistan, Myanmar, and China. The peridot from Pakistan, often referred to as "Kohistan Neon," is particularly prized for its intense, vibrant green color and exceptional clarity, making it more valuable than commercial-grade material.
Spinel is a magnesium aluminum oxide (MgAl₂O₄) and forms in a variety of geological settings, most commonly in metamorphic rocks like marble and alluvial deposits. Unlike peridot, which is often associated with volcanic activity, spinel is found in the same environments as ruby and sapphire, leading to its historical misidentification. Major sources for fine spinel include Myanmar (Burma), which is renowned for producing the most vivid red and pink spinels. Sri Lanka is another critical source, particularly for high-quality blue and pink spinels. Other sources include Vietnam, Tanzania, and Tajikistan. The gem's formation in these metamorphic and alluvial contexts means it is often found in secondary deposits, where it has been transported from its original host rock by water or other natural forces.
Gemological Properties
Understanding the physical and optical properties of peridot and spinel is essential for appreciating their value and care requirements. The following table summarizes key gemological data for both stones, based on information derived from the provided sources.
| Property | Peridot (Olivine) | Spinel |
|---|---|---|
| Chemical Formula | (Mg,Fe)₂SiO₄ | MgAl₂O₄ |
| Crystal System | Orthorhombic | Cubic |
| Hardness (Mohs Scale) | 6.5 - 7 | 8 |
| Refractive Index | 1.65 - 1.69 | 1.718 - 1.736 |
| Specific Gravity | 3.34 - 3.45 | 3.58 - 3.61 |
| Common Colors | Olive green to yellow-green | Red, pink, blue, purple, black, colorless |
| Durability | Fairly good; can be prone to chipping due to poor cleavage | Excellent; high hardness and no cleavage make it very durable |
| Treatment Status | Generally untreated; some material may be oiled or treated for clarity | Often untreated; heat treatment is common and generally stable |
Peridot is characterized by its distinctive olive to yellow-green color, caused by iron impurities in its crystal structure. Its hardness on the Mohs scale ranges from 6.5 to 7, making it suitable for most types of jewelry but requiring some care to avoid scratches. It has no cleavage, but it is brittle and can chip if struck hard. Peridot is typically found in transparent to translucent forms, and while inclusions are common, eye-clean stones are available. The most valued peridots exhibit a rich, vibrant green with minimal brownish tones.
Spinel boasts superior hardness at 8 on the Mohs scale, making it one of the most durable gemstones for daily wear. Its cubic crystal structure gives it exceptional brilliance and fire. Spinel occurs in a wide array of colors, with the most valuable being the vivid reds (often compared to ruby) and neon pinks. Blue spinel is also highly sought after. Unlike peridot, spinel is rarely treated, and its color is generally natural. Its durability, combined with its stunning visual properties, makes it an excellent choice for all types of jewelry, including rings and bracelets.
Market Value and Appeal
The market value of peridot and spinel varies significantly based on color, clarity, size, and origin. Both gems offer compelling options for different budgets and preferences.
Peridot is generally more affordable than many other colored gemstones, primarily due to its relative abundance. Commercial-grade peridot (1–5 carats) wholesales for approximately $10–$40 per carat. However, fine peridot from premier sources like Pakistan or Myanmar commands higher prices due to superior clarity and size. The "Kohistan Neon" peridot from Pakistan can exceed $200 per carat. On average, high-quality peridot falls within the $200 to $1,000 per carat range. Its vibrant green color and cosmic origins—some peridots are found in meteorites—add to its appeal, making it a fascinating yet accessible choice.
Spinel has seen a significant increase in value and recognition in recent years. While often overshadowed by ruby, fine spinel can rival ruby in price. Exceptional red and cobalt blue spinels are the most valuable, with prices for vivid reds or neon pinks (1–3 carats) easily fetching $600 to over $2,000 per carat retail. Rare, top-quality spinel can reach $500 to $5,000 per carat or more, rivaling the cost of traditional gemstones like aquamarine and sapphire. Its durability and brilliance make it a hidden gem among collectors and a smart choice for those seeking value and longevity.
Symbolism and Metaphysical Beliefs
Both peridot and spinel are rich in symbolism, though their attributed powers differ based on their unique histories and properties.
Peridot, with its connection to the sun and light, has long been associated with protection, healing, and good fortune. Ancient Egyptians believed it could ward off evil spirits and nightmares. It is often called the "evening emerald" because its green color is visible even in low light. Metaphysically, peridot is linked to the heart chakra, promoting emotional balance, compassion, and forgiveness. It is also believed to attract abundance, prosperity, and success, making it a popular stone for those seeking to manifest their goals.
Spinel, while historically confused with ruby, has accumulated its own set of beliefs. It is often associated with revitalization and energy renewal. Its vibrant colors are thought to inspire passion, creativity, and motivation. Some traditions link spinel to the root and heart chakras, believing it can help overcome lethargy and promote a sense of stability and grounding. As a gemstone that has been rediscovered and appreciated in its own right, spinel symbolizes resilience and the uncovering of hidden truths.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of both peridot and spinel, though their different hardness levels require slightly different approaches.
Peridot, with a hardness of 6.5 to 7, should be protected from hard blows and abrasive materials. It is safe to clean with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as the stone's brittleness makes it susceptible to fracture from sudden temperature changes. Store peridot jewelry separately from harder stones to prevent scratching. It is also advisable to remove peridot rings during heavy manual work to avoid chipping.
Spinel, with a hardness of 8, is much more durable and resistant to scratches. It can be cleaned using an ultrasonic cleaner (if the stone is eye-clean) or with warm, soapy water and a soft brush. While spinel is tough, it is still recommended to store it in a separate pouch or compartment to avoid scratches from other gemstones. Its durability makes it an excellent choice for everyday wear, including in rings and bracelets that are subject to more wear and tear.
Conclusion
The August birthstones, peridot and spinel, offer a compelling study in contrasts. Peridot, with its ancient origins and sunny green hue, provides an accessible and symbolically rich option for those born in the month. Spinel, with its exceptional durability, brilliant sparkle, and history of being mistaken for ruby, presents a more durable and often more valuable alternative. Together, they cover a wide spectrum of colors, price points, and aesthetic preferences. Whether drawn to peridot's connection to the Earth's mantle or spinel's resilience and vibrant palette, individuals born in August have the privilege of choosing between two gems that are both scientifically fascinating and deeply symbolic. Their combined presence in the birthstone calendar enriches the tradition, offering choice and depth to the celebration of an August birthday.