The August Birthstone: Peridot - A Gem of Volcanic Fire and Ancient Legend

Peridot, with its distinctive olive-green hue, stands as the traditional birthstone for the month of August. This captivating gem is one of the few minerals found in two distinct geological environments: the deep Earth's mantle and the fiery depths of volcanoes. Its journey from molten rock to a polished gemstone is a story of geological drama, making it a subject of intense interest for gemologists, collectors, and jewelry enthusiasts alike. As an August birthstone, peridot carries with it a rich tapestry of history, lore, and scientific intrigue. This article will explore the comprehensive world of peridot, from its formation within the Earth to its celebrated status in modern jewelry, drawing exclusively on the provided source materials to present an authoritative guide to this remarkable green gem.

History and Lore

Peridot's history is as deep and layered as the gemstone itself, with roots stretching back to ancient civilizations. The gemstone has been mined and prized for over 3,500 years, with its most ancient and significant source being the island of Zabargad, also known as St. John's Island, in the Red Sea. Historical records indicate that this island was the primary source of peridot for the ancient Egyptian civilization. The Egyptians referred to peridot as the "gem of the sun" and believed it possessed the power to ward off evil and protect the wearer during the night. Cleopatra, the famed Egyptian queen, was known to have a collection of peridot gemstones, which were often mistaken for emeralds due to their vibrant green color. The gemstone was so highly valued that it was used to adorn the robes of Egyptian pharaohs and was believed to have been found in the "Topazius" mines of ancient Egypt, a name that has caused some historical confusion with other yellow gemstones.

The use of peridot extended beyond Egypt. The Romans also held peridot in high esteem, valuing it for its beauty and believed it could be used to predict the future and provide protection from evil spirits. During the Middle Ages, peridot was brought to Europe by Crusaders, where it was often set in religious jewelry. The famous "The Three Magi" shrine in the Cologne Cathedral features a large peridot, believed to have been one of the gifts brought by the Magi. In the 18th century, peridot was rediscovered in Europe, leading to a resurgence in its popularity, particularly in the Baroque and Victorian eras, where it was used extensively in elaborate jewelry designs.

The modern designation of peridot as the birthstone for August is a more recent development. The tradition of assigning specific gemstones to each month of the year has evolved over centuries, with the most widely recognized list being the modern birthstone list established by the American National Retail Jewelers Association (now Jewelers of America) in 1912. Peridot was officially included as the birthstone for August on this list, a status it has maintained ever since, alongside other stones like sardonyx and spinel in some traditional lists. Its vibrant green color is often associated with summer, making it a fitting gem for the warmest month of the year.

Geological Formation and Sources

Peridot is the gemological variety of the mineral olivine, specifically the magnesium-rich end-member known as forsterite (Mg₂SiO₄). Its formation process is unique among gemstones. Unlike many gems that crystallize in pegmatites or metamorphic rocks, peridot is formed deep within the Earth's mantle. The primary source of gem-quality peridot is from kimberlite and basaltic volcanic eruptions, which act as a conduit, bringing mantle-derived peridot crystals to the surface in a process known as a "volcanic birth." These crystals are often found in peridotite xenoliths—fragments of the mantle rock carried up by the magma.

The most historically significant source is the island of Zabargad (St. John's Island) in the Red Sea. This location is unique because it is one of the few places where peridot is found in dunite, a type of peridotite. The island's peridot deposits are believed to be of mantle origin and were the source of the gems worn by ancient Egyptians. The mining on Zabargad was extensive, and historical accounts describe the difficult conditions under which the gemstones were extracted.

In the modern era, the primary sources of peridot have shifted. The largest and most important deposits are located in the San Carlos Apache Indian Reservation in Arizona, USA. These deposits were discovered in the late 19th century and are the most significant source of peridot in the world today, producing gem-quality material in a wide range of sizes and colors. The peridot from Arizona is often found in basalt flows, which is consistent with its volcanic origin.

Other notable sources include: - Pakistan: The Kohistan region in northern Pakistan is known for producing large, high-quality peridot crystals, often found in gabbro and dunite. - Myanmar (Burma): Peridot is found in the Mogok region, a famous gemstone area, often associated with marble deposits. - China: Significant deposits are found in the Xinjiang region. - Brazil: Peridot is found in basalt deposits in the states of Minas Gerais and Pará. - Australia: The New England region in New South Wales has produced peridot. - Egypt: While the historic mines on Zabargad are largely depleted, small-scale mining still occurs, and Egyptian peridot remains highly prized for its historical significance and color.

The formation of peridot in the mantle means it is brought to the surface relatively quickly by geological standards. This rapid ascent helps preserve the gem's quality, as it does not spend prolonged periods at temperatures and pressures that could cause alteration or degradation. However, the gem is also found in alluvial deposits, where it has been eroded from its original host rock and transported by water, often resulting in rounded, polished natural crystals.

Gemological Properties

Peridot is distinguished by a unique combination of gemological properties that make it both beautiful and scientifically interesting. Its most defining characteristic is its color, which ranges from a light, yellowish-green to a deep, olive-green. The color is primarily due to the presence of iron (Fe) within its chemical structure. Unlike many other gemstones, peridot's color is not typically influenced by heat treatment; its natural hue is stable and does not fade with exposure to light.

The following table summarizes the key gemological properties of peridot, as derived from the provided sources:

Hardness and Durability: With a hardness of 6.5 to 7 on the Mohs scale, peridot is durable enough for everyday wear in jewelry, such as rings and pendants. However, it is not as hard as sapphire or diamond (both 9 on the Mohs scale), so it can be scratched by harder materials. Its toughness is rated as fair to poor due to its poor cleavage in two directions. Cleavage refers to the tendency of a mineral to break along flat planes; peridot's cleavage makes it more susceptible to chipping or breaking if struck with sufficient force. This property requires careful setting and handling in jewelry design, often recommending protective settings like bezels for rings.

Color and Clarity: The most valued peridot colors are a rich, vibrant olive-green without strong brown or yellow overtones. The presence of iron determines the hue, with higher iron content leading to a deeper green. Peridot is often found with inclusions, which are natural internal features. The most famous inclusion is the "lily pad" inclusion, which consists of small, round, disk-like formations that can resemble lily pads floating on water. These inclusions are a hallmark of natural peridot and can be used to distinguish it from synthetic or imitated materials. Fingerprint inclusions, which look like the pattern of a human fingerprint, are also common. While inclusions can affect clarity and value, many peridot gems are cut to minimize their visibility.

Cut and Carat Weight: Peridot is typically cut into faceted rounds, ovals, and cushions to maximize its brilliance and color. The gem's vitreous luster gives it a bright, sparkling appearance when well-cut. Peridot crystals can be found in large sizes, with gems over 10 carats being relatively common. In fact, some of the largest faceted peridots in the world, such as the 310-carat gem in the Smithsonian Institution, originate from the San Carlos Apache Reservation in Arizona. Larger, clean, and well-colored peridots are highly prized by collectors and jewelers.

Synthetic and Imitation Peridot: The sources note that synthetic peridot, created using the Czochralski method or other flux-growth techniques, is available but is not widely produced or marketed. Synthetic peridot is chemically and physically identical to its natural counterpart, making it difficult to distinguish without advanced gemological testing. Imitation peridot, such as glass or colored cubic zirconia, is more common and can be identified by its lack of natural inclusions and different optical properties.

Symbolism and Metaphysical Beliefs

Beyond its physical beauty and scientific properties, peridot is steeped in a rich history of symbolism and metaphysical beliefs. For centuries, various cultures have attributed powerful meanings and healing properties to this green gemstone.

As previously mentioned, the ancient Egyptians revered peridot as the "gem of the sun." They believed it had the power to protect against nightmares and evil spirits, especially when set in gold. The gem was also thought to bring the wearer good fortune, health, and peace. Its association with the sun linked it to vitality, growth, and renewal, themes that resonate with its vibrant green color, reminiscent of nature and spring.

In medieval Europe, peridot was considered a stone of compassion and healing. It was believed to have the power to soothe anger, alleviate guilt, and promote forgiveness. Some legends held that peridot could be used to treat asthma and other respiratory ailments, and that it had a calming effect on the nervous system. It was also associated with the heart chakra, promoting emotional balance and attracting love and friendship.

In modern crystal healing practices, peridot is often referred to as the "stone of prosperity" and "the gem of abundance." It is believed to attract wealth, success, and good luck, both in personal and professional endeavors. Its green color is linked to the heart and growth, making it a popular stone for those seeking to open their hearts to new experiences, heal emotional wounds, and foster a sense of gratitude and optimism.

Peridot is also the traditional gift for the 16th wedding anniversary, symbolizing enduring love and happiness. Its durability and lasting color make it a fitting emblem for a long-lasting partnership. While these metaphysical beliefs are not scientifically verified, they form an important part of peridot's cultural legacy and add to its appeal for many gemstone enthusiasts.

Care and Cleaning

Proper care is essential to maintain the beauty and longevity of peridot jewelry. While peridot is relatively durable, its specific properties—particularly its moderate hardness and poor cleavage—require careful handling and cleaning methods.

Cleaning: Peridot can be safely cleaned using warm, soapy water and a soft brush. A mild dish soap dissolved in lukewarm water is ideal. Gently scrub the gemstone with a soft-bristled brush, such as a toothbrush, to remove any dirt or oils from the setting and the gem's surface. Rinse thoroughly with clean water to remove all soap residue. Avoid using harsh chemicals, such as bleach or ammonia, as they can damage the gemstone or its setting. Ultrasonic cleaners and steam cleaners are not recommended for peridot. The vibrations from an ultrasonic cleaner can cause existing fractures or cleavages to worsen, leading to chipping or breakage. Steam cleaning can also be risky due to the potential for thermal shock.

Storage: When not being worn, peridot jewelry should be stored separately from other jewelry to prevent scratches. It is best to keep it in a soft cloth pouch or a lined jewelry box with compartments. Avoid storing peridot pieces where they can come into contact with harder gemstones like diamonds, sapphires, or rubies, which can scratch its surface.

Wearing Precautions: Due to its fair to poor toughness, it is advisable to avoid wearing peridot rings or bracelets during activities that could subject the gem to hard impacts, such as gardening, sports, or heavy manual work. For rings, a protective setting like a bezel or a halo can help shield the gemstone from accidental knocks. Peridot is generally safe for everyday wear in pendants and earrings, where it is less likely to be struck.

Exposure to Chemicals and Heat: Peridot should be protected from prolonged exposure to strong acids and chemicals, which can etch or damage the gem's surface. This includes household cleaners, cosmetics, and hairsprays. It is also advisable to remove peridot jewelry before swimming in chlorinated pools or hot tubs. While peridot is stable at normal temperatures, sudden and extreme temperature changes should be avoided to prevent potential thermal stress.

By following these simple care guidelines, the vibrant green color and brilliance of peridot can be preserved for generations, ensuring that this August birthstone remains a cherished part of any jewelry collection.

Conclusion

Peridot, the traditional birthstone for August, is a gem of remarkable geological origin, historical depth, and enduring beauty. Formed in the fiery depths of the Earth's mantle and brought to the surface by volcanic activity, its journey is as dramatic as its vibrant olive-green hue. From its ancient origins on the Red Sea island of Zabargad, where it was cherished by Egyptian pharaohs, to its modern-day prominence in the mines of Arizona, peridot has captivated humanity for millennia. Its unique gemological properties, including its distinctive inclusions and moderate hardness, make it a fascinating subject for study and a durable choice for fine jewelry. While its metaphysical beliefs add a layer of spiritual significance, it is the gemstone's intrinsic scientific and historical value that solidifies its status as a treasured birthstone. For gemstone enthusiasts, jewelry buyers, and students of gemology, peridot offers a compelling blend of science, history, and artistry, making it a truly exceptional gem to own, study, and admire.

Sources

1. James Allen - August Birthstone Ring
2. Gemological Institute of America (GIA) - Peridot
3. International Gem Society (IGS) - Peridot
4. Geology.com - Peridot
5. Jewelers of America - Birthstones
6. Mindat.org - Olivine Group
7. Smithsonian National Museum of Natural History - Gem Collection
8. Royal Ontario Museum - Peridot
9. British Museum - Collection Highlights
10. University of Cambridge - Earth Sciences