Peridot, the vibrant green gemstone designated for the month of August, holds a unique position in the world of gemology. Unlike many birthstones that have been associated with a single month for centuries, peridot’s modern status as an August birthstone is a relatively recent development, yet its history stretches back to ancient civilizations. This gem, a transparent variety of the silicate mineral olivine, is prized for its distinctive yellowish-green hue and remarkable origins. While not as historically revered as diamond or ruby, peridot has carved out a niche as a gem of the sun, celebrated for its unique color, relative durability, and intriguing geological formation. The following exploration delves into the multifaceted world of peridot, examining its historical journey, geological sources, gemological properties, cultural symbolism, and practical care, drawing exclusively from the available gemological and historical data.
History and Lore
The story of peridot begins in antiquity, where it was often mistaken for other green gems due to its similar appearance. Historical records and archaeological finds indicate that peridot was mined and used as early as the 15th century B.C. on the island of Zabargad (St. John’s Island) in the Red Sea. This ancient source provided gems that were highly valued in the Egyptian, Greek, and Roman worlds. The Egyptians referred to peridot as the “gem of the sun,” believing it possessed the power of the sun god Ra. They associated it with nature deities and thought it could ward off evil spirits and night terrors. This belief was so strong that peridot was often set in gold and worn as talismans, particularly by royalty and priests.
In Hawaiian legend, peridot stones are considered the tears of the goddess Pele, the deity of volcanoes and fire. This connection to a powerful, natural force underscores the gem’s deep ties to the earth and its fiery origins. The name “peridot” itself has a somewhat murky etymology. It is derived from the Medieval Latin peridotus, which may have referred to this gem or to other gems of a similar green color. Another potential origin is the Arabic word faridat, meaning “gemstone.”
Despite its ancient pedigree, peridot’s association with the month of August is a modern convention. The traditional birthstone list for August, established in the early 20th century, included sardonyx. Peridot was added as a modern alternative and has since gained significant popularity, often overshadowing its traditional counterpart. This shift reflects a broader trend in birthstone lists, where newer, more commercially available stones are introduced alongside or in place of older ones. For example, the traditional birthstone for June is pearl, but the modern list includes alexandrite, a much rarer and more expensive gem. Similarly, for October, tourmaline was added as a modern alternative to the traditional opal.
Geological Formation and Sources
Peridot is a gem variety of the mineral olivine, specifically the magnesium-rich end-member known as forsterite. Its formation is unique among gemstones, as it is not typically found in granite or pegmatite deposits like many other gems. Instead, peridot is formed deep within the Earth’s mantle under extreme heat and pressure. It is brought to the surface through volcanic activity. Large crystals can be found in certain types of volcanic rocks called basalts and peridotites. This origin story gives peridot a direct connection to the planet’s interior forces.
The most famous historical source of gem-quality peridot was the island of Zabargad in the Red Sea, which produced large, fine-quality crystals for centuries. However, this source is no longer a significant producer. Today, peridot is mined in several locations around the world. The United States has notable deposits, particularly in Arizona (the San Carlos Apache Reservation), New Mexico, and Hawaii. The Arizona peridot mines are known for producing small to medium-sized gems with a vibrant green color.
Other significant sources include Pakistan, which is known for producing large peridot crystals, and China. Myanmar (Burma) and Australia also have peridot deposits. The gem’s color can vary depending on its source. For instance, peridot from Pakistan often has a rich, pure green hue, while stones from Arizona may show a more yellowish-green tone. This variation is due to subtle differences in the iron and trace element content within the crystal structure.
While peridot is not considered a rare gemstone in general, large stones with a pure, vibrant green color are scarce. Most commercial peridot on the market is found in smaller sizes, typically under 10 carats. Gems over 10 carats are considered rare and command significantly higher prices. The availability of peridot in larger sizes is one of the factors that has made it an attractive option for statement jewelry, offering a bold pop of color that is more affordable than some other large green gems like emerald.
Gemological Properties
Understanding the physical and optical properties of peridot is essential for gemologists, jewelers, and consumers alike. These characteristics define its durability, appearance, and value.
Color: Peridot is celebrated for its signature green color, which ranges from light green to yellowish-green and brownish-green. The most prized color is a vibrant, pure green, often with a slight yellow tint. This yellowish-green hue is a key identifier, distinguishing it from emerald, which typically has a bluish or pure green tone. The color in peridot is caused by the presence of iron within its chemical structure. The specific shade can vary significantly based on the stone’s origin. Larger peridot crystals tend to exhibit the most desirable green color, while smaller stones may show a more yellowish or brownish cast.
Luster and Transparency: Peridot possesses a characteristic glassy or vitreous luster, giving it a bright, reflective surface when cut and polished. It is typically transparent to translucent, with the finest gem-quality specimens being clear and transparent with minimal inclusions.
Hardness and Durability: On the Mohs scale of hardness, peridot rates between 6.5 and 7. This places it in a moderately durable category, suitable for most types of jewelry, including rings, earrings, and pendants. However, its hardness is lower than that of sapphire (Mohs 9) or diamond (Mohs 10), so it is more susceptible to scratching and abrasion. Peridot has no cleavage, which is a favorable trait, meaning it does not have any natural planes of weakness that could cause it to split along a particular direction. However, it is somewhat brittle and can be chipped or fractured if struck with sufficient force. This makes it important to consider the setting and wear habits when choosing peridot jewelry, particularly for rings that are subject to daily impact.
Refractive Index and Double Refraction: Peridot has a relatively high refractive index, which contributes to its brilliance. A notable optical property is its strong double refraction (birefringence). When viewed through a loupe, this can cause the edges of facets or inclusions to appear doubled. This characteristic is a useful diagnostic tool for gemologists identifying peridot.
Chemical Formula: The chemical formula for peridot (olivine) is (Mg, Fe)₂SiO₄. It is a silicate mineral, specifically a member of the olivine group. The iron content is what gives peridot its green color; higher iron content generally results in a deeper green hue.
Other Properties: Some peridot crystals may exhibit fluorescence under ultraviolet light. The gem is also known for its inclusion patterns. Common inclusions can include small, needle-like crystals, which are sometimes referred to as “lily pad” inclusions, and fluid inclusions. While these inclusions can affect clarity, they are also natural indicators of the gem’s origin and authenticity.
Symbolism and Metaphysical Beliefs
Beyond its physical properties, peridot is steeped in symbolism and metaphysical beliefs that span centuries and cultures. As mentioned, the ancient Egyptians revered it as the “gem of the sun,” associating it with light, warmth, and protection. They believed it could ward off evil spirits and night terrors, which is why it was often set in gold and worn after dark. This protective quality was linked to the gem’s lively appearance and its connection to the sun’s power.
In Hawaiian culture, peridot’s formation from volcanic activity led to its association with the goddess Pele. The stones were seen as tangible tears of the goddess, embodying the fierce, creative, and destructive energy of the volcano. This connection gives peridot a symbolism of transformation, passion, and the raw power of nature.
Metaphysically, peridot is often called the “stone of compassion.” It is believed to have a calming energy that can relieve stress, anger, and jealousy, promoting feelings of peace and well-being. Some traditions hold that peridot can open the heart to new relationships and foster loyalty and commitment. It is also associated with prosperity and abundance, thought to attract wealth and success to the wearer.
In modern crystal healing practices, peridot is linked to the heart chakra, believed to help heal emotional wounds and release negative patterns. Its green color is naturally associated with growth, renewal, and the vitality of nature. While these beliefs are not supported by scientific evidence, they contribute to the gem’s enduring appeal and cultural significance.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of peridot jewelry. Given its moderate hardness and brittleness, it requires thoughtful handling and cleaning methods.
Storage: When not worn, peridot jewelry should be stored separately from other gemstones and metals to prevent scratching. A soft cloth pouch or a compartmentalized jewelry box is ideal. Avoid storing it with diamonds, sapphires, or rubies, which are much harder and can scratch the peridot surface.
Cleaning: Peridot can be safely cleaned using warm, soapy water and a soft brush. A mild detergent is sufficient; avoid harsh chemicals or abrasive cleaners. Gently scrub the stone and setting with a soft-bristled toothbrush, paying attention to the back of the stone and the setting where dirt can accumulate. Rinse thoroughly with clean water and pat dry with a soft, lint-free cloth.
Avoid Ultrasonic and Steam Cleaners: It is generally not recommended to clean peridot in an ultrasonic cleaner or with steam. The vibrations from an ultrasonic cleaner can potentially cause fractures in stones with existing inclusions or weak points. Steam cleaners can also be risky due to the gem’s potential for thermal shock, especially if the stone has been treated or has inclusions.
Avoid Chemicals and Extreme Temperatures: Peridot should be removed before swimming in chlorinated pools, using household cleaners, or applying lotions and perfumes, as chemicals can damage the stone’s surface or alter its appearance. Sudden temperature changes can also cause damage, so it’s best to avoid exposing peridot to extreme heat or cold.
Professional Maintenance: For jewelry with peridot settings, it is advisable to have it checked by a professional jeweler periodically. The jeweler can inspect the setting to ensure the stone is secure, check for any damage, and perform a professional cleaning if needed.
Conclusion
Peridot, with its distinctive green hue and unique geological origin, stands as a captivating and significant birthstone for August. Its history, from ancient Egyptian reverence to its modern status as a popular gemstone, reflects a journey of enduring appeal. While not as historically prominent as some of the more traditional precious gems, peridot’s combination of beauty, durability, and relative affordability makes it a favorite among gemstone enthusiasts and jewelry buyers. Its formation deep within the Earth’s mantle and its journey to the surface via volcanic activity give it a story that is as compelling as its color. Understanding its gemological properties, from its hardness and inclusions to its color variations, allows for informed appreciation and care. Whether valued for its symbolic meanings of protection and compassion or simply admired for its vibrant, sunlit green, peridot continues to shine as a gemstone of warmth, vitality, and natural beauty.