August, the month of summer, is uniquely distinguished in the world of birthstones for offering not one, but three gemstones: sardonyx, peridot, and spinel. Each of these stones carries a rich legacy of historical significance, gemological properties, and cultural symbolism. Together, they form a diverse palette of colors—from deep reds and blacks to vibrant greens and soothing pinks and reds—offering an array of choices for those born in August and for those seeking meaningful jewelry.
This article provides an in-depth exploration of the August birthstones, tracing their origins, examining their physical and chemical properties, and uncovering the cultural and historical roles they have played throughout the centuries. The article also includes care tips and insights into the modern appreciation of these stones, particularly the relatively recent recognition of spinel as an August birthstone in 2016.
The Evolution of August Birthstones
The tradition of assigning gemstones to each month of the year is ancient, but the list of August’s birthstones has evolved over time. Originally, sardonyx was the sole August birthstone, a status it held for thousands of years. Sardonyx, a banded chalcedony composed of sard and onyx layers, was used in ancient Egypt for seals and signet rings, and its popularity has endured through various cultures and epochs.
In the early 20th century, as gemology advanced and more gemstones became widely available and identifiable, the Jewelers of America updated the birthstone list in 1912 to include peridot as an additional August birthstone. Peridot, known for its vibrant green color, has been treasured for millennia and is often referred to as the "gem of the sun."
Decades later, in 2016, the Jewelers of America and the American Gem Trade Association expanded the list further by adding spinel to the August birthstone roster. This addition was driven by a desire to increase awareness of spinel, a gemstone frequently mistaken for ruby due to its similar red hue, and to provide August-born individuals with even more options to express their individuality through gemstones.
The inclusion of these three gemstones reflects not only the evolving nature of gemology but also the growing appreciation for a wider range of stones in the jewelry industry.
Sardonyx: The Ancient August Birthstone
Historical Significance and Symbolism
Sardonyx, the original August birthstone, has been revered for over 4,000 years, with its use dating back to the 2nd Dynasty of Egypt. This gemstone is composed of alternating bands of sard (a reddish-brown chalcedony) and onyx (a white or black chalcedony). The distinct layering of sardonyx made it a popular material for seals, signet rings, and cameos.
Ancient Egyptians attributed healing properties to sardonyx, believing it could mend bones. In the Old Testament, sardonyx is mentioned as one of the stones in the High Priest’s breastplate, symbolizing spiritual strength. Roman soldiers wore sardonyx rings engraved with Mars, the god of war, for protection in battle. During the Renaissance, sardonyx was worn by public speakers and orators for its supposed power of eloquence and was believed to help single women attract their ideal partners.
Geological Formation and Sources
Sardonyx is a type of chalcedony, a cryptocrystalline form of quartz. It forms in sedimentary rocks and is typically found in volcanic or metamorphic environments. The stone is best known for its striated appearance, where layers of sard and onyx create a visually striking pattern.
The major source of sardonyx is India, particularly for stones with strong color contrast between the sard and onyx layers. Other notable sources include Brazil, Germany, Czechoslovakia, Madagascar, Uruguay, and the United States. These deposits have yielded sardonyx in various colors and banding patterns, though the Indian sardonyx is most highly prized for its clarity and contrast.
Gemological Properties
Sardonyx is a silica-based mineral with a Mohs hardness of 6.5 to 7, making it relatively durable but not as hard as gems like quartz or topaz. It is typically translucent to opaque and is often carved into cameos, intaglios, and seals. The stone is generally polished to a high luster, enhancing the visibility of its banded layers.
Unlike many gemstones, sardonyx is not commonly faceted but is instead sculpted into shapes that emphasize its natural banding. It is heat-resistant and stable under normal wear, though it should be protected from sudden temperature changes and harsh chemicals.
Peridot: The Vibrant Green Gem of the Sun
Historical Background and Misidentifications
Peridot, the second August birthstone, has a long and fascinating history. Known as the "gem of the sun", peridot is a yellowish green to greenish yellow gemstone that has been cherished for its vibrant color and unique brilliance. Peridot is a variety of the mineral olivine, which is formed under extreme geological conditions, often brought to the surface through volcanic activity or found in meteorites.
Historically, peridot was often mistaken for other gemstones such as topaz and emerald. For example, the Shrine of the Three Holy Kings in Germany’s Cologne Cathedral is adorned with what were believed to be emeralds, but are in fact peridots. Some historians speculate that Cleopatra’s famous emerald collection may have actually been composed of peridots.
The name "peridot" is derived from the French word "perit," meaning "to pass through," which may refer to its translucent nature or to the way it was traded through the Red Sea island of Topazios, a source of peridot that was once thought to be the source of topaz.
Geological Formation and Sources
Peridot forms in the Earth’s mantle, where it is carried to the surface by volcanic activity. It is also found in meteorites, making it one of the few gemstones with an extraterrestrial origin. Peridot is composed of iron and magnesium silicate, with its green color coming from the presence of iron.
Major sources of peridot include:
- Zabargad Island (St. John's Island) in the Red Sea, historically one of the most important sources.
- Arizona, where peridot is found in basaltic lava flows and is sometimes referred to as "Arizona peridot."
- Madagascar, Pakistan, and Brazil, which also produce high-quality peridot.
Peridot is relatively common compared to other gemstones, but stones with a rich, deep green color and high clarity are highly valued.
Gemological Properties
Peridot has a Mohs hardness of 6.5 to 7, making it suitable for everyday wear in properly designed jewelry. It is isotropic, meaning it does not have double refraction, and it has a glassy luster when polished. Peridot is typically transparent to translucent and is often cut into round brilliant, mixed, or emerald cuts to maximize its color and brilliance.
Peridot is sensitive to heat and sudden temperature changes, so it should be avoided in soldering processes during jewelry making. It is also soluble in strong acids, so care should be taken to avoid exposure to harsh chemicals.
Spinel: The Sparkling Addition to August’s Birthstone Triad
Introduction and Historical Misidentification
Spinel, the newest addition to August’s birthstone list (added in 2016), is a silicate mineral that occurs in a wide range of colors, including red, pink, blue, white, and black. Spinel is often mistaken for ruby, especially when it appears in deep red hues. In fact, many historical "rubies" in royal collections were actually spinel.
Spinel has a Mohs hardness of 8, making it harder than peridot and more durable than sardonyx. It is composed of aluminum and magnesium oxides, with its color determined by trace elements such as chromium (for red) and iron (for black or blue).
The name "spinel" is derived from the Latin word "spina," meaning "thorn", a reference to the prismatic crystal structure of the mineral.
Geological Formation and Sources
Spinel is found in metamorphic and igneous rocks, often in association with marble or garnet-rich deposits. Notable sources of spinel include:
- Myanmar, known for producing spinels in hot pink and red.
- Sri Lanka, which yields blue, pink, and purple spinels, particularly in the Central Highlands and Ratnapura District.
- Vietnam, where the Luc Yen region produces spinels in deep red, purple, pink, and blue.
- Tanzania, where pinkish and orangy-red spinel was discovered in 2007.
- Pakistan, Afghanistan, and India, which also have significant spinel deposits.
Spinel is relatively rare compared to many other gemstones, especially in vibrant colors, which contributes to its value.
Gemological Properties
Spinel is isotropic like peridot, meaning it does not exhibit double refraction. It has a glassy to vitreous luster and is often transparent to translucent. Spinel is available in a wide range of colors, making it a versatile gemstone for jewelry.
Spinel is harder than peridot and is more resilient to wear and tear, making it suitable for daily wear in rings and bracelets. It is also stable under normal conditions and can be cleaned with warm, soapy water and a soft brush.
Spinel is not commonly irradiated or heat-treated to enhance its color, which makes it a natural gemstone with minimal enhancement.
Historical and Cultural Significance
Spinel has been historically undervalued due to its frequent misidentification with ruby. However, in recent years, spinel has gained popularity as a distinct gemstone with its own unique beauty and charm. It is now recognized as a valuable alternative to ruby, especially in red and pink tones.
Spinel is also a traditional gift for 22nd wedding anniversaries, symbolizing passion and enduring love. Its addition to the August birthstone list in 2016 reflects the growing appreciation for this gemstone and its increasing recognition in the jewelry industry.
Choosing the Perfect August Birthstone
With three gemstones to choose from, those born in August have the luxury of variety. Each stone offers a unique combination of beauty, history, and symbolism, allowing individuals to select a birthstone that resonates with their personal style and values.
- Sardonyx is ideal for those who appreciate ancient history and symbolism, and who enjoy the artistic appeal of carved cameos and seals.
- Peridot is a great choice for those drawn to sunlight and vibrant color, with its green brilliance and warm energy.
- Spinel is perfect for those who want a versatile gemstone with sparkling colors and durability, especially in red, pink, and blue.
When selecting August birthstone jewelry, it is important to consider the care and maintenance of each stone. Sardonyx should be protected from harsh chemicals, peridot should be avoided in high heat environments, and spinel, while durable, should be cleaned gently to maintain its luster.
Conclusion
The triad of August birthstones—sardonyx, peridot, and spinel—offers a rich tapestry of color, history, and symbolism. Each gemstone has a unique story, from the ancient Egyptian use of sardonyx to the sunlit brilliance of peridot and the sparkling versatility of spinel. The evolution of the August birthstone list reflects not only the advancements in gemology but also the growing appreciation for a wider range of gemstones.
For those born in August, these gemstones are more than just ornamental treasures; they are symbols of individuality, history, and personal connection. Whether chosen for their aesthetic appeal, historical significance, or cultural meaning, these stones continue to capture the hearts and imaginations of gemstone enthusiasts around the world.