August is a unique month in the world of birthstones, offering a trio of distinct gems rather than a single option. While modern lists often highlight peridot as the primary birthstone, historical and traditional lists also embrace the banded chalcedony known as sardonyx and the versatile spinel. This diversity provides those born in August with a remarkable range of choices, each with its own deep geological origins, captivating history, and unique symbolism. Peridot, with its warm green hue, is often the most recognized, earning the nickname "evening emerald" for its ability to sparkle in low light. Sardonyx, one of the oldest known gem materials, has been prized for millennia for its use in cameos and seals. Spinel, a relative newcomer to the birthstone list, has a history of being mistaken for more famous gems like ruby but now stands celebrated for its own vibrant palette. This article will explore the geological formation, historical significance, gemological properties, and care for these three remarkable August birthstones, drawing on authoritative sources to provide a comprehensive guide for enthusiasts, collectors, and students of gemology.
History and Lore
The histories of the August birthstones are as varied as the stones themselves, spanning ancient civilizations and evolving through centuries of trade and discovery. Peridot’s past is particularly rich with misidentification and legend. Often confused with emeralds and topazes throughout history, peridot’s true identity was sometimes obscured. The Red Sea island of Topazios, a name historically linked to topaz, was in fact a significant source of peridot. Some historians even speculate that Cleopatra’s famed emerald collection may have largely been composed of peridot. This gem was known as the "gem of the sun" in ancient times, valued for its bright green color. The word "peridot" is derived from the Arabic faridat, meaning gem. It appeared in priests’ jewelry as early as the second century BCE and later adorned chalices and churches in medieval Europe. Peridot was also used as a protective talisman, believed to shield the owner from evil spirits and "terrors of the night." The Shrine of the Three Holy Kings in Germany’s Cologne Cathedral is decorated with 200 carats of gems long believed to be emeralds but are, in fact, peridot. Ancient Romans called it the "evening emerald" because its sparkle remained vivid even in low light, a quality that distinguished it from other green gems.
Sardonyx boasts an even more ancient pedigree, with a history dating back more than 4,000 years. As a variety of chalcedony, a microcrystalline form of quartz, sardonyx was popular for jewelry and carvings since antiquity. Its distinctive bands of white, brown, and red made it ideal for cameos and seals, which were used for official documents and personal adornment. The stone’s use in medieval Europe is well-documented, with sardonyx artifacts found in shrines. A notable historical reference includes Queen Elizabeth I gifting a sardonyx to the Earl of Essex, illustrating its value in royal courts. Its enduring popularity for engraved jewelry and its association with strength and protection have made it a timeless choice.
Spinel, the newest addition to the August birthstone lineup, was officially added to the modern birthstone list in 2016. Its history, however, is long and often misunderstood. For centuries, red spinel was mistaken for ruby, leading to its inclusion in many famous royal collections under the wrong name. Some of the most famous "rubies" in the British Crown Jewels, for example, are actually large red spinels. This historical confusion led to spinel being underappreciated. It was not until modern gemological science could reliably distinguish between the two that spinel began to gain recognition for its own merits. Today, consumers seeking an alternative to ruby often turn to spinel for its vibrant colors and relative affordability.
Geological Formation and Sources
The geological origins of these three gems are as diverse as their appearances, each forming under unique conditions within the Earth and, in one case, from beyond it.
Peridot is unique among gemstones as it is formed deep within the Earth’s mantle. Unlike most gems that crystallize from magma, peridot is brought to the surface by volcanic and tectonic activity. It is the gem variety of the mineral olivine. Some peridot has even journeyed to Earth on meteorites, making it one of the few gems with an extraterrestrial origin. Major sources for gem-quality peridot today include China, Myanmar (Burma), Pakistan, Tanzania, Vietnam, and the United States. Arizona is a significant producer of peridot in the U.S., particularly from the San Carlos Apache Reservation. The oldest and most historically significant source is the Egyptian island of Zabargad (formerly Topazios) in the Red Sea. Mining on this harsh island may have begun as early as 340–279 BCE. Peridot from Zabargad is still highly prized by collectors for its historical significance and quality.
Sardonyx, being a variety of chalcedony, forms in low-temperature environments, typically in volcanic or sedimentary rocks. It is composed of silicon dioxide and is characterized by its distinct bands of color, which result from the alternating layers of sard (a reddish-brown variety of chalcedony) and onyx (a black or white variety). While specific mining locations for sardonyx are not detailed in the provided sources, its formation as a banded chalcedony places it in the same geological family as other agates and onyxes, found in various parts of the world.
Spinel forms in metamorphic rocks, particularly in magnesium-rich environments. It can also occur in alluvial deposits, having been eroded from its original host rock. Historically, the most famous source of red spinel was the Badakhshan region of Afghanistan, which supplied the "Balas Rubies" to the markets of Asia and Europe. Other sources include Myanmar (Burma), Sri Lanka, and Thailand. The variety of colors available in spinel—from pink and red to blue, purple, and even black—reflects the different trace elements present during its formation.
Gemological Properties
Understanding the physical and optical properties of these birthstones is essential for identification, valuation, and care. The following table summarizes key gemological data for peridot, sardonyx, and spinel, based on established gemological standards.
| Property | Peridot | Sardonyx | Spinel |
|---|---|---|---|
| Mineral Family | Olivine | Chalcedony (Quartz) | Spinel |
| Chemical Formula | (Mg,Fe)₂SiO₄ | SiO₂ | MgAl₂O₄ |
| Crystal System | Orthorhombic | Trigonal (microcrystalline) | Cubic |
| Hardness (Mohs) | 6.5 – 7 | 6.5 – 7 | 7.5 – 8 |
| Refractive Index | 1.65 – 1.69 | 1.54 – 1.55 | 1.71 – 1.73 |
| Specific Gravity | 3.34 – 3.51 | 2.65 | 3.60 – 3.70 |
| Color Range | Yellowish-green to olive-green | Bands of white, brown, red, black | Wide range: red, pink, blue, purple, black, colorless |
| Clarity | Typically has inclusions; "lily pad" inclusions common | Opaque to translucent; banded pattern is characteristic | Often eye-clean; may have inclusions like fingerprint patterns |
| Durability | Fairly good, but can be brittle due to cleavage; suitable for jewelry with care | Good durability due to hardness; good for carvings and cameos | Excellent durability, very hard and resistant to scratching |
Peridot is a relatively hard gem (6.5-7 on the Mohs scale) but has a tendency to cleave, meaning it can break along specific planes if struck with force. This makes it important to protect peridot jewelry from hard impacts. Its distinctive green color comes from iron content, and it is pleochroic, showing slightly different shades of green when viewed from different angles. A well-cut peridot exhibits excellent brilliance and fire.
Sardonyx shares the hardness of quartz (6.5-7) and is quite durable. Its defining feature is its banding, which is created by layers of different colored chalcedony. The contrast between the bands—typically white or black against a reddish-brown background—is what makes it ideal for carving and cameos, where the pattern can be highlighted in the final design.
Spinel is the hardest and most durable of the three, with a Mohs hardness of 7.5 to 8. This makes it an excellent choice for all types of jewelry, including rings that are worn daily. It has a high refractive index, giving it a bright, vitreous luster. Red spinel, in particular, can be exceptionally vibrant, though it lacks the strong dichroism seen in ruby. Spinel is often found in large, clean crystals, allowing for the creation of sizable faceted gems.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, the August birthstones are imbued with a rich tapestry of symbolism and metaphysical beliefs, many of which have persisted from ancient times to the present day.
Peridot has been associated with light, protection, and prosperity for millennia. As the "gem of the sun," it was believed to capture and hold sunlight, providing the wearer with protection from darkness and evil forces. Ancient cultures considered it a powerful talisman against night terrors and demons. Its green color, reminiscent of nature, led to associations with growth, renewal, and health. Some traditions linked peridot to heart chakra healing, promoting emotional balance and well-being. It is also traditionally given to celebrate a 16th wedding anniversary.
Sardonyx carries symbolism rooted in strength, courage, and communication. In ancient Rome, it was worn by soldiers and orators to gain courage and eloquence. As a stone of the earth, it is believed to provide stability and grounding. Its layered bands symbolize the integration of different aspects of the self and the ability to communicate complex ideas clearly. In some belief systems, sardonyx is associated with happiness and marital fidelity, making it a popular choice for engagement rings and other symbolic jewelry.
Spinel, particularly the red variety, has long been called the "stone of immortality." It is believed to revitalize, rejuvenate, and provide a sense of renewed energy and vitality. Spinel is also associated with clearing negative thoughts and emotions, promoting a positive outlook and mental clarity. Different colors of spinel are thought to have specific properties; for example, blue spinel is linked to calmness and spiritual insight, while pink spinel is associated with love and compassion. Its recent addition to the birthstone list has allowed modern wearers to connect with these ancient metaphysical associations while enjoying a gem of exceptional beauty and durability.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone jewelry. The physical properties of peridot, sardonyx, and spinel dictate specific cleaning and handling recommendations.
Peridot, with its hardness of 6.5-7 and cleavage, requires gentle handling. It is susceptible to scratching and can be damaged by sharp blows. To clean peridot, use warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as sudden temperature changes and vibrations can cause fractures. It is also advisable to remove peridot jewelry before engaging in strenuous activities or household chores to prevent impact damage.
Sardonyx, being a variety of quartz, is quite durable and can be cleaned using the same method as peridot: warm, soapy water and a soft brush. Its hardness makes it resistant to scratching, but it is still wise to store it separately from harder gems like diamonds or sapphires to avoid abrasion. Ultrasonic cleaners are generally safe for sardonyx, but it is always best to check with a professional jeweler if the piece includes other materials or settings that may be sensitive.
Spinel is the most durable of the three, with excellent hardness and no cleavage. It is very resistant to scratching and can withstand more vigorous cleaning methods. Warm, soapy water and a soft brush are perfectly suitable. Spinel can also be safely cleaned in an ultrasonic cleaner, though caution is advised if the stone is set in a delicate or old piece of jewelry. Steam cleaning is also generally safe, but as with all gems, it is prudent to ensure the stone is free of fractures or inclusions that could be exacerbated by heat.
For all three gems, it is recommended to store them in a soft cloth or a separate compartment in a jewelry box to prevent them from scratching each other or being scratched by other pieces. Periodic professional inspection of the jewelry settings is also advisable to ensure the stones remain securely held.
Conclusion
The August birthstones—peridot, sardonyx, and spinel—offer a compelling narrative that intertwines geology, history, and human belief. Peridot, born of the Earth’s fiery mantle and even the cosmos, captivates with its "evening emerald" glow and ancient lore of protection. Sardonyx, with its millennia-old history as a carved gem, symbolizes strength and communication, its banded layers telling a story of time and formation. Spinel, long mistaken for ruby, has emerged from the shadows to be recognized for its own exceptional brilliance and durability, offering a vibrant palette of colors. Together, they provide August-born individuals with a remarkable spectrum of choices, each stone carrying a legacy of scientific wonder and cultural significance. Whether chosen for its historical depth, its geological uniqueness, or its symbolic meaning, each of these gems serves as a timeless and personal emblem for the month of August.