The month of August is uniquely represented by a trio of distinct gemstones: peridot, spinel, and sardonyx. This diverse selection reflects a complex history of gemological confusion, cultural significance, and evolving market preferences. Peridot, the yellowish-green to greenish-yellow variety of the mineral olivine, is celebrated for its extraterrestrial origins and historical misidentification with emeralds and topaz. Spinel, a gemstone available in a wide spectrum of colors, has long been undervalued, often mistaken for ruby, yet possesses its own rich history and metaphysical lore. Sardonyx, a banded form of chalcedony, holds the title of the original August birthstone, with a lineage tracing back over 4,000 years to ancient biblical and Roman contexts. Together, these stones offer a fascinating study in gemology, from the deep Earth and meteorite origins of peridot to the ancient carving traditions of sardonyx and the recent renaissance of spinel as a sought-after alternative to ruby.
History and Lore: A Journey from Ancient Seals to Modern Lists
The historical narrative of August’s birthstones is one of transformation and occasional misconception. The original gemstone for August, as established in ancient tradition, was sard, a dark red variety of chalcedony. This stone, known as odem in Hebrew, was listed among the twelve gems on the High Priest’s breastplate in the Old Testament and was identified as the sixth Foundation Stone in the Book of Revelation. Its connection to the zodiac sign Virgo, which partially overlaps with August, solidified its early status as a birthstone. Over time, the lighter, orangey shade of sard—carnelian—became more widely recognized, particularly in Jewish culture, Rome, Italy, and Spain. From the 1400s to the early 1900s, Europe generally celebrated carnelian as the August gemstone.
A pivotal shift occurred in 1912 when a decision by American jewelers effectively removed carnelian from the official birthstone list. This decision, however, did not erase sard entirely; its banded counterpart, sardonyx, endured. Sardonyx, a stone featuring alternating layers of brownish-red to dark orange sard and white or black onyx, was designated as an August birthstone in Poland and Arab culture. Its banded appearance, while distinct from the original solid-colored sard, allowed it to maintain a foothold in tradition. The interchangeability of the terms sard and sardonyx in historical texts, even among scholars like the 1st-century Jewish historian Josephus, contributed to sardonyx’s survival as an alternate gemstone. For millennia, sardonyx was prized in ancient Rome for seals and signet rings, as hot wax would not adhere to its surface, and it was a popular material for cameos and intaglios.
Peridot’s history is marked by persistent confusion with other gems. The mineral olivine, from which peridot is derived, has been mistaken for topaz and emerald for centuries. The Red Sea island of Topazios, a source that lent its name to topaz, was actually a producer of peridot. Perhaps the most famous example of this confusion involves Cleopatra’s renowned emerald collection; some historians speculate that the gems in her collection were, in fact, peridot. Furthermore, the 200-carat gems adorning the Shrine of the Three Holy Kings in Germany’s Cologne Cathedral, long believed to be emeralds, are now confirmed to be peridot. The name “peridot” is believed to originate from the Arabic word faridat, meaning gem. Another theory suggests a Greek origin from peridona, meaning “giving plenty,” which aligns with the gemstone’s associations with prosperity and good fortune. Peridot has been valued in many ancient and medieval cultures, and the oldest-recorded source is the Egyptian island of Zabargad.
Spinel’s history is one of overlooked value. For centuries, red spinel was mistaken for ruby, with many historical "rubies" actually being spinel. One of the most famous examples is the Black Prince’s Ruby, a large red spinel that Henry V wore on his helmet at the Battle of Agincourt, where it is said to have deflected a fatal blow. This gemstone, which comes in a variety of colors including red, pink, orange, purple, blue, and green, was historically underappreciated. It is only recently that consumers have begun to seek out spinel as a distinct and valuable gemstone in its own right, particularly as an alternative to ruby.
In 2016, the American Gem Trade Association added spinel to the official list of modern birthstones for August, making it the third gemstone for the month alongside peridot and sardonyx. This addition further diversified the August birthstone palette, creating a trio that spans the color wheel: green peridot, banded sardonyx, and red spinel.
Geological Formation and Sources
The geological origins of the three August birthstones are remarkably diverse, ranging from deep within the Earth’s mantle to outer space.
Peridot is formed under extreme conditions. It is the gem variety of the mineral olivine, which is a common rock-forming mineral in the Earth’s upper mantle. The gemstone can be brought to the surface by volcanic activity, often found in hardened lava. Uniquely, peridot is also found in meteorites that have traveled from outer space, making it one of the few gemstones with extraterrestrial origins. Major mining sites for peridot include the Egyptian island of Zabargad (also known as St. John’s Island or Topazios), as well as locations in China, Myanmar, Pakistan, Tanzania, Vietnam, and the United States.
Spinel is a magnesium aluminum oxide (MgAl₂O₄) that forms in metamorphic rocks and alluvial deposits. While the provided sources do not specify particular mining locations for spinel, they note its occurrence in a wide color range, which influences its geological formation conditions. The gem’s history of being mistaken for ruby suggests that it was often sourced from the same regions as corundum (ruby and sapphire), such as Southeast Asia and the Indian subcontinent.
Sardonyx is a banded variety of chalcedony, which itself is a microcrystalline form of quartz (silicon dioxide, SiO₂). The bands of sardonyx are formed by alternating layers of sard (the dark red to brownish variety of chalcedony) and onyx (typically white or black chalcedony). This banding occurs during the formation of the silica-rich layers in volcanic or sedimentary environments. The sources indicate that sardonyx has many sources worldwide. India is noted for producing sardonyx with good contrast between the colored layers, which is highly desirable for carving. Other localities include Brazil, Germany, Czechoslovakia, Madagascar, Uruguay, and the United States.
Gemological Properties
The three gemstones exhibit distinct physical and chemical characteristics, which influence their use in jewelry and care requirements.
| Gemstone | Mineral Species | Chemical Formula | Typical Colors | Hardness (Mohs Scale) | Notable Properties |
|---|---|---|---|---|---|
| Peridot | Olivine | (Mg, Fe)₂SiO₄ | Yellowish green to greenish yellow | Not explicitly stated in sources | Formed in Earth's mantle and meteorites. |
| Spinel | Spinel | MgAl₂O₄ | Red, pink, orange, purple, blue, green | Not explicitly stated in sources | Often mistaken for ruby. |
| Sardonyx | Chalcedony (Quartz) | SiO₂ | Bands of brownish-red to dark orange (sard) with white or black (onyx) | 6.5 to 7 | A banded variety of chalcedony. |
Peridot is defined as the yellowish green to greenish yellow gem variety of the mineral olivine. Its specific chemical composition is (Mg, Fe)₂SiO₄, indicating it is a solid solution between forsterite (Mg₂SiO₄) and fayalite (Fe₂SiO₄). The provided sources do not specify its hardness on the Mohs scale, but as a member of the olivine group, it typically ranges between 6.5 and 7. Its refractive index and specific gravity are also not detailed in the provided materials.
Spinel is a magnesium aluminum oxide with the chemical formula MgAl₂O₄. It is known for its wide color range, which includes red, pink, orange, purple, blue, and green. The red variety is particularly notable for its historical confusion with ruby. The sources do not provide specific gemological data such as hardness, refractive index, or specific gravity for spinel.
Sardonyx is a banded variety of chalcedony, which is the microcrystalline form of quartz (SiO₂). Its hardness is explicitly stated to be 6.5 to 7 on the Mohs scale, making it durable enough for jewelry but requiring care to avoid scratches. The bands consist of sard (dark red to brown) and onyx (white or black). It is important to note that sardonyx, like other forms of chalcedony, is commonly dyed to enhance or alter its color. High heat, such as that used in jewelry manufacturing or repair, can affect the color of dyed sardonyx. Ultrasonic and steam cleaners should be used with caution for this gemstone.
Symbolism and Metaphysical Beliefs
Each of the August birthstones carries its own set of symbolic meanings and metaphysical associations, often rooted in ancient beliefs and historical use.
Sardonyx has a long history of symbolic significance. As one of the stones in the High Priest’s breastplate, it is believed to represent the strength of spiritual life. In ancient Rome, soldiers wore sardonyx rings carved with the image of Mars, the god of war, seeking protection in battle. Today, this August birthstone is associated with courage, happiness, and clear communication. It is also believed to bring stability to marriage and partnerships, making it a meaningful gem for relational harmony.
Peridot is linked to prosperity and good fortune, a symbolism reinforced by one theory of its name deriving from the Greek word peridona, meaning “giving plenty.” Its historical confusion with emeralds and topaz has also imbued it with the attributes of those gems, such as healing and protection. In ancient and medieval cultures, peridot was highly valued, and its association with light and the sun (due to its bright green color) may contribute to beliefs in its positive and energizing properties.
Spinel, while historically undervalued, has accumulated its own lore. The famous Black Prince’s Ruby (a red spinel) is a testament to the stone’s perceived protective powers, as it was believed to have saved Henry V’s life. Modern metaphysical beliefs often associate spinel with revitalization and overcoming lethargy. Its variety of colors allows for different associations; for example, red spinel may be linked to passion and energy, while blue spinel could be connected to calm and communication.
The collective symbolism of the August trio—green peridot, banded sardonyx, and red spinel—spans a broad emotional and spiritual spectrum, from the prosperity and light of peridot to the courage and communication of sardonyx and the revitalization and protection of spinel.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these gemstones, and the requirements vary based on their physical properties.
Peridot is a relatively durable gemstone, though its specific hardness is not listed in the sources. As with any gemstone, it is advisable to avoid harsh chemicals, extreme temperatures, and physical impacts. Cleaning peridot jewelry with warm, soapy water and a soft brush is generally safe.
Spinel is known for its durability. While the sources do not specify its hardness, spinel is a hard and stable gemstone, typically ranking 8 on the Mohs scale. It is resistant to chemicals and heat, making it relatively easy to care for. Warm, soapy water and a soft brush are effective for cleaning. Ultrasonic and steam cleaners are usually safe for untreated spinel, but caution is advised for stones that may have been fracture-filled or treated.
Sardonyx, with a hardness of 6.5 to 7 on the Mohs scale, requires careful handling to prevent scratches. It is particularly susceptible to damage from high heat and harsh chemicals, especially if it has been dyed. High heat can alter the color of dyed sardonyx, and chemicals may strip the dye. Therefore, ultrasonic and steam cleaners should be used with caution, if at all. The safest method for cleaning sardonyx is with warm, soapy water and a soft cloth. For jewelry set with sardonyx, it is best to remove it during activities that could subject it to hard knocks or exposure to chemicals.
Conclusion
The August birthstones—peridot, spinel, and sardonyx—offer a rich tapestry of gemological diversity, historical intrigue, and cultural significance. From the extraterrestrial origins of peridot and its centuries-long confusion with emeralds to the underappreciated beauty of spinel, once mistaken for ruby, and the ancient, banded legacy of sardonyx, each stone tells a unique story. Their journey to becoming a trio of birthstones reflects the evolving nature of gemology, market trends, and cultural preferences. Today, they stand together as a testament to the enduring appeal of gemstones, providing individuals born in August with a choice of stones that embody a wide range of colors, properties, and meanings, from prosperity and courage to revitalization and clear communication.