The modern birthstone list, established by the American Gem Trade Association (AGTA) in 1912 and later updated, assigns specific gemstones to each month. For the months of August and December, two distinct and historically significant stones are featured: Peridot for August and Turquoise for December. While these gemstones are unrelated in composition and formation, both possess rich histories, unique geological origins, and deep cultural symbolism that have cemented their status as cherished birthstones. This article explores the gemological properties, historical lore, and modern significance of Peridot and Turquoise, drawing upon established gemological knowledge and historical records.
Peridot, a gem variety of the mineral olivine, is celebrated for its distinctive olive-green hue, which ranges from yellow-green to brown-green. It is one of the few gemstones that occurs in a single color family, though its exact shade is determined by its iron content. Historically, peridot has been associated with light and protection, with ancient civilizations believing it to be a gift from the Earth's core. For December, Turquoise is the designated birthstone, a hydrous phosphate of copper and aluminum known for its sky-blue to greenish-blue color. Turquoise has been revered for millennia across various cultures, often symbolizing protection, health, and good fortune. Both stones, despite their differences, share a common thread of being among the oldest gemstones used in human adornment and ritual.
The following sections will delve into the historical journey of these gems, from their ancient origins to their inclusion in modern birthstone lists. We will examine the geological processes that create them and the primary sources of these materials today. A detailed analysis of their gemological properties will provide the scientific basis for their identification and valuation. Furthermore, the article will explore the enduring symbolism and metaphysical beliefs attached to Peridot and Turquoise, offering insight into why they continue to captivate gem enthusiasts and jewelry buyers. Finally, practical advice on the care and maintenance of these stones will be provided, ensuring their beauty can be preserved for generations.
Historical Origins and the Path to Birthstone Status
The history of Peridot and Turquoise is as deep as the mines from which they are extracted, with each stone traveling a unique path through human civilization before finding a formal place on the birthstone calendar.
Peridot: The Gem of the Sun
Peridot has a history that stretches back to ancient Egypt, where it was known as the "gem of the sun." The Egyptians mined peridot on the island of Zabargad (also known as St. John's Island) in the Red Sea as early as 1500 B.C. This source was so significant that the gem was often mistaken for emeralds, and many historical "emeralds" in royal collections, including those of Cleopatra, are now believed to be peridot. The stone was used in jewelry and religious artifacts, and it was believed to protect against nightmares and evil spirits. The Romans also valued peridot, calling it "topazion," and used it for adornment. Through the Middle Ages, peridot was primarily used by the Catholic Church, often set in the chalices and reliquaries of clergy, as it was thought to bring divine inspiration. Its journey to becoming a modern birthstone for August was formalized in 1912 when the National Association of Jewelers (now the Jewelers of America) established the first official birthstone list, which included peridot as the primary stone for the eighth month.
Turquoise: The Stone of the Sky
Turquoise is one of the oldest known gemstones, with evidence of its use dating back over 6,000 years to ancient Egypt and Mesopotamia. In ancient Persia (modern-day Iran), turquoise was revered as a sacred stone, symbolizing the heavens and believed to offer protection from unnatural death. It was extensively used in the adornment of royalty and in religious contexts. The stone's name derives from the French "pierre tourque" or "Turkish stone," as it was first brought to Europe from Turkey via the Silk Road. Native American cultures, particularly the Navajo, Zuni, and Pueblo tribes of the Southwestern United States, have a profound connection with turquoise, using it in intricate jewelry and ceremonial objects for centuries, where it represents life, health, and spiritual protection. The December birthstone designation also dates to the 1912 AGTA list, where turquoise was assigned as one of the stones for the final month of the year, a position it has held ever since, also sharing the month with lapis lazuli and zircon in some lists.
Geological Formation and Global Sources
The formation of Peridot and Turquoise occurs through vastly different geological processes, resulting in distinct mining locations and material characteristics.
Peridot: From the Mantle to the Earth's Surface
Peridot is formed under extreme conditions deep within the Earth's mantle. It is a primary mineral that crystallizes from magma, typically in ultramafic rocks like peridotite. The gemstone is brought to the surface through volcanic activity or tectonic processes. The most significant historical source was the island of Zabargad in the Red Sea, which was mined for centuries until the 20th century. Today, the primary commercial sources of gem-quality peridot include: * Pakistan: The Kohistan-Eternity region in the Himalayas is a major source, producing large, high-quality crystals. * United States: The San Carlos Apache Reservation in Arizona is a notable source, producing peridot in a range of sizes, though often with inclusions. * Myanmar (Burma): Known for producing peridot with exceptional clarity and color. * China: The Xinjiang region has emerged as a significant producer in recent decades. * Other locations include Australia, Brazil, Egypt, and Norway, though production from these areas is often smaller in scale or of lower gem quality.
Turquoise: A Secondary Mineral Formation
Unlike peridot, turquoise is a secondary mineral formed by the interaction of water with pre-existing rocks containing copper, aluminum, and phosphorus. This process occurs in arid or semi-arid regions where water can percolate through copper-rich rocks, dissolving and then re-precipitating the turquoise in fractures and veins. The quality and color of turquoise are heavily influenced by the specific mineral composition of the host rock. The most renowned sources include: * United States (Southwest): Arizona, New Mexico, and Nevada are famous for their turquoise mines. Key historical and current mines include the Sleeping Beauty mine in Arizona (known for its pure, light blue color), the Morenci mine (historically significant), and the Kingman mine in Nevada. The "Royston" and "Turf" mines are also well-known. * Iran (Persia): The Nishapur region has been the source of the finest "Persian turquoise" for millennia, prized for its uniform, sky-blue color. * China: China is a major producer of turquoise today, with mines in the Hubei province yielding material that is often stabilized (treated) to enhance durability and color. * Other sources include Afghanistan, Chile, and Egypt, though production from these regions is generally smaller.
Gemological Properties
Understanding the physical and chemical properties of Peridot and Turquoise is essential for identification, valuation, and proper care. The following table summarizes key gemological data for both stones.
| Property | Peridot (Olivine) | Turquoise |
|---|---|---|
| Chemical Formula | (Mg,Fe)₂SiO₄ | CuAl₆(PO₄)₄(OH)₈·4H₂O |
| Crystal System | Orthorhombic | Triclinic |
| Hardness (Mohs Scale) | 6.5 - 7 | 5 - 6 (often softer in porous varieties) |
| Specific Gravity | 3.27 - 4.37 | 2.60 - 2.90 |
| Refractive Index | 1.65 - 1.69 | 1.61 - 1.65 |
| Birefringence | 0.036 - 0.038 | 0.040 (often not observed due to lack of transparency) |
| Inclusions | Common; often contains "lily pad" inclusions, needles, or fluid inclusions. | Opaque; often has a matrix (host rock) or spiderweb veining. |
| Color Range | Yellow-green to brown-green. | Sky-blue to greenish-blue. |
| Transparency | Transparent to translucent. | Opaque. |
| Luster | Vitreous (glass-like). | Waxy to subvitreous. |
| Durability | Fairly good, but can be brittle due to poor cleavage. | Fair, but soft and porous; susceptible to cracking, chipping, and chemical damage. |
Peridot: A Stone of Iron and Light
Peridot's color is directly tied to its iron content; higher iron levels produce a deeper, more brownish-green hue, while lower iron results in a lighter, yellowish-green. The most valued peridot is a vibrant, pure olive-green without secondary hues. Its hardness of 6.5 to 7 on the Mohs scale makes it suitable for most jewelry, but it requires care due to its poor cleavage (a tendency to break along specific planes). It is not as durable as sapphire or diamond but is harder than many other colored stones like opal or tanzanite. Peridot is rarely treated, and its color is natural. However, it can be confused with other green stones like tourmaline or zircon, making gemological testing important for identification.
Turquoise: A Delicate and Complex Gem
Turquoise is unique among birthstones due to its opacity and porous nature. Its color is determined by the amount of copper (blue) and iron (green) in its composition. The most prized turquoise is a uniform, robin's-egg blue, often from Persian sources. American turquoise often exhibits a matrix, which is the host rock (such as limonite or ironstone) that remains within the turquoise, creating distinctive patterns like spiderweb or speckled designs. Due to its softness and porosity, turquoise is almost always treated. The most common treatments include stabilization (impregnating the stone with a clear resin or wax to improve durability and color) and dyeing (to enhance or alter color). Natural, untreated turquoise is rare and commands a high premium. Its properties make it vulnerable to heat, chemicals, and prolonged exposure to sunlight, which can cause fading or damage.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, Peridot and Turquoise are steeped in symbolism and metaphysical lore, beliefs that have persisted for centuries and continue to influence their appeal today.
Peridot: The Stone of Renewal and Protection
Peridot has long been associated with light, growth, and protection. In ancient times, it was believed to ward off evil spirits and protect the wearer from the "evil eye." Its connection to the sun led to associations with vitality, energy, and renewal. In modern crystal healing, peridot is often linked to the heart chakra, thought to promote emotional healing, reduce stress, and attract abundance and prosperity. It is also considered a stone of forgiveness, helping to release past resentments and foster new beginnings. For those born in August, peridot is said to bring good luck, peace, and success, and to enhance confidence and self-esteem.
Turquoise: The Stone of Protection and Communication
Turquoise is perhaps one of the most universally protective stones in gem lore. Across cultures, it has been worn as an amulet to guard against accidents, illness, and negative energies. The Native Americans believe it to be a living stone that changes color to warn of danger or illness. It is also associated with the throat chakra, believed to enhance communication, creativity, and honest self-expression. In Persian tradition, turquoise is a symbol of purity and is thought to bring balance and alignment to the mind and body. For December-born individuals, turquoise is said to offer protection, promote good fortune, and bring inner calm and tranquility. It is also considered a stone of friendship and loyalty, often given as a gift to signify these bonds.
Care and Cleaning
Proper maintenance is crucial for preserving the beauty and integrity of both Peridot and Turquoise, given their distinct properties.
Caring for Peridot
Due to its good hardness and lack of cleavage, peridot is relatively durable for everyday wear. However, it is susceptible to thermal shock and can be damaged by extreme temperature changes. It is also sensitive to harsh chemicals and acids, which can etch its surface. * Cleaning: Use warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaners, as the vibrations and heat can cause fractures. Rinse thoroughly and dry with a soft, lint-free cloth. * Storage: Store peridot jewelry separately to prevent scratching by harder stones like sapphire or diamond. A soft pouch or a lined jewelry box is ideal.
Caring for Turquoise
Turquoise requires more delicate handling due to its lower hardness and porous nature. It is highly sensitive to chemicals, including cosmetics, perfumes, lotions, and even acidic perspiration, which can cause discoloration and damage the stone's surface. * Cleaning: Use only a soft, damp cloth to wipe the stone. Avoid soaps, detergents, and any cleaning solutions. Never use ultrasonic cleaners, steam cleaners, or ammonia-based solutions, as these can dissolve the stone or damage its treatment. * Storage: Store turquoise away from direct sunlight to prevent fading. Keep it in a separate, soft pouch to avoid scratches from other jewelry. It is advisable to put turquoise jewelry on last when dressing and remove it first when undressing to minimize exposure to chemicals and physical impact.
Conclusion
Peridot and Turquoise, the designated birthstones for August and December, represent two distinct yet equally fascinating chapters in the story of gemstones. Peridot, with its radiant olive-green hues and deep roots in ancient Egyptian lore, offers a connection to the Earth's fiery interior and symbolizes renewal and protection. Turquoise, the sky-blue stone of protection and communication, carries the weight of millennia of cultural reverence, from the empires of Persia to the deserts of the American Southwest. Both stones, while differing in hardness, composition, and appearance, share a common legacy as objects of beauty, belief, and enduring value. For the gem enthusiast, the jewelry buyer, or the student of gemology, understanding the unique properties and histories of Peridot and Turquoise provides a deeper appreciation for their role not only as birthstones but as timeless treasures of the mineral world.