The month of August is associated with three distinct birthstones: peridot, spinel, and sardonyx. Each of these gemstones has a rich history, unique gemological properties, and a set of cultural and symbolic meanings that have been passed down through centuries. This article explores the characteristics, geological origins, historical significance, and modern uses of these August birthstones, providing a comprehensive overview for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
Peridot is believed to have one of the most fascinating geological histories of any gemstone. It is formed under extreme conditions, often found in the hardened lava that carried it from deep within Earth’s mantle or in meteorites that have traveled from outer space. The historical significance of peridot is equally compelling. For centuries, it was often mistaken for other gems, such as emerald and topaz. The Red Sea island of Topazios, from which the name "topaz" is derived, is known to have produced peridot, contributing to the confusion between the two gems.
The Shrine of the Three Holy Kings in Cologne Cathedral in Germany is a notable historical site where peridot has been used. This shrine is adorned with 200 carats of gemstones that were once thought to be emeralds but are, in fact, peridot. The gem’s historical confusion is further highlighted by the speculation that Cleopatra’s famous emerald collection may have actually been peridot.
Spinel, another August birthstone, was historically underappreciated and often mistaken for ruby and other red gemstones. This misidentification persisted for centuries until gemologists developed the tools and knowledge to distinguish spinel from its more famous counterparts. A notable discovery in Tanzania in 2007 brought attention to the beauty and variety of spinel, particularly in pinkish and orangy red hues, which have captivated gem collectors.
Sardonyx, the original August birthstone, has a history that dates back more than 4,000 years. It is a combination of two types of chalcedony: sard and onyx. The alternating bands of sard (brownish red to dark orange) and onyx (white or black) make it a popular material for carvings such as cameos and intaglios. In ancient Rome, sardonyx was widely used for seals and signet rings due to its resistance to the heat of melted wax. Roman soldiers wore sardonyx rings with images of Mars carved on them for protection in battle. This gemstone is also believed to have been one of the stones in the High Priest’s breastplate, as mentioned in the Old Testament, symbolizing the strength of spiritual life.
Geological Formation and Sources
The formation and source locations of these August birthstones vary significantly, reflecting their diverse geological origins.
Peridot is formed in the Earth’s mantle and brought to the surface through volcanic activity. It can also be found in meteorites, making it one of the few gemstones with an extraterrestrial origin. The most notable sources of peridot include Arizona in the United States, Brazil, China, Egypt, and India. Arizona is particularly famous for producing the highest quality peridot, which is known for its vibrant green color.
Spinel is found in a variety of locations around the world, with notable deposits in Afghanistan, Burma (Myanmar), Sri Lanka, and Tanzania. The 2007 discovery in Tanzania of pinkish and orangy red spinel brought renewed attention to this gemstone, showcasing its beauty and versatility. Spinel's formation is similar to that of corundum, but it has a different chemical composition, which gives it distinct optical and physical properties.
Sardonyx is a form of chalcedony and is found in several countries, including India, Brazil, Germany, Czechoslovakia, Madagascar, Uruguay, and the United States. India is particularly known for producing sardonyx with excellent contrast between the different colored layers. The gemstone is also commonly dyed to enhance or alter its colors, which requires careful handling during manufacturing and repair to avoid damaging the coloration.
Gemological Properties
Understanding the gemological properties of these August birthstones is essential for both collectors and jewelers, as it helps in identifying, evaluating, and caring for these gems.
Peridot
- Chemical Formula: (Mg,Fe)₂SiO₄
- Hardness: 6.5 to 7 on the Mohs scale
- Color: Yellowish green to greenish yellow
- Refractive Index: 1.65 to 1.70
- Specific Gravity: 3.32 to 3.37
- Crystal System: Orthorhombic
Peridot is known for its vibrant green color, which is due to the presence of iron in its chemical composition. It is relatively soft compared to other gemstones, so it requires careful handling to avoid scratches and damage. Its refractive index and specific gravity are consistent with its mineral composition, making it relatively easy to identify.
Spinel
- Chemical Formula: MgAl₂O₄ (magnesium aluminum oxide)
- Hardness: 8 on the Mohs scale
- Color: Red, pink, orange, blue, purple, and black
- Refractive Index: 1.718
- Specific Gravity: 3.6 to 4.0
- Crystal System: Cubic
Spinel is a versatile gemstone with a wide range of colors, including the popular red and pink varieties. It is harder than peridot, making it more durable for use in rings and other jewelry. Spinel has a high refractive index, which contributes to its brilliance and fire. Its cubic crystal system gives it a distinct optical behavior that is useful in gem identification.
Sardonyx
- Chemical Formula: SiO₂ (silicon dioxide)
- Hardness: 6.5 to 7 on the Mohs scale
- Color: Alternating bands of sard (brownish red to dark orange) and onyx (white or black)
- Refractive Index: 1.48 to 1.53
- Specific Gravity: 2.60 to 2.64
- Crystal System: Trigonal (as chalcedony)
Sardonyx is a form of chalcedony and is known for its distinct banding, which makes it ideal for carvings and cameos. Its hardness is similar to that of peridot, and it requires careful handling to avoid damage. The refractive index and specific gravity are consistent with other forms of chalcedony, and the gemstone is often dyed to enhance its colors.
Symbolism and Metaphysical Beliefs
Each of these August birthstones carries its own set of symbolic meanings and metaphysical properties, which have been passed down through various cultures and traditions.
Peridot is often associated with renewal, healing, and positive energy. It is believed to bring balance and harmony to the mind and body, making it a popular choice for those seeking emotional stability. In ancient times, peridot was considered a gemstone of light and was used to ward off nightmares and negative thoughts. It is also believed to promote self-confidence and encourage personal growth.
Spinel is associated with courage, vitality, and emotional strength. It is believed to enhance love and relationships, making it a popular choice for engagement rings and other romantic jewelry. The gemstone is also thought to bring clarity and focus, helping individuals make important decisions with confidence and insight.
Sardonyx is believed to bring courage, happiness, and clear communication. It is often associated with stability in marriage and partnerships, making it a meaningful choice for those seeking long-term relationships. Roman soldiers wore sardonyx rings with images of Mars carved on them for protection in battle, highlighting its association with strength and bravery. It is also believed to promote spiritual growth and the strength of the soul.
Care and Cleaning
Proper care and cleaning are essential for maintaining the beauty and longevity of these August birthstones. Each gemstone has specific requirements due to its hardness, composition, and sensitivity to heat and chemicals.
Peridot should be cleaned using warm soapy water and a soft-bristle brush, as ultrasonic and steam cleaners can cause damage. Due to its relatively low hardness, peridot should be handled with care to avoid scratches and chips. It is also sensitive to high heat, which can cause discoloration or fading.
Spinel is more durable than peridot and can be cleaned using ultrasonic and steam cleaners. However, the presence of fractures or inclusions may make it vulnerable to damage. Warm soapy water is a safe alternative for cleaning, and spinel should be protected from high heat, as some colors may fade when exposed to extreme temperatures.
Sardonyx is a form of chalcedony and is relatively durable, but it should be handled with care, especially as a ring. It is often dyed, so high heat from jewelry manufacturing or repair can affect the coloration. Ultrasonic and steam cleaners should be used with caution, and warm soapy water is the safest option for cleaning. Sardonyx should also be protected from harsh chemicals, which can damage its surface.
Conclusion
The August birthstones—peridot, spinel, and sardonyx—each offer a unique combination of beauty, history, and symbolism. Peridot, with its vibrant green color and extraterrestrial origins, is a gemstone of renewal and healing. Spinel, once mistaken for ruby, is now appreciated for its wide range of colors and durability. Sardonyx, the original August birthstone, has a rich history in ancient Rome and continues to be valued for its distinct banding and symbolic meanings.
Understanding the gemological properties, historical significance, and care requirements of these stones is essential for anyone interested in collecting or wearing them. Whether used in jewelry, as a collectible, or for its metaphysical properties, each of these August birthstones has its own story to tell. As the appreciation for these gemstones continues to grow, they remain a timeless and meaningful choice for those born in the month of August.