The month of August is uniquely represented by three distinct gemstones: peridot, spinel, and sardonyx. This trio offers a remarkable spectrum of color, from the vibrant olive-green of peridot to the fiery reds and blues of spinel and the striking banding of sardonyx. Each stone carries its own rich history, geological origin, and set of gemological properties, providing a diverse palette for those born in this summer month. The inclusion of multiple stones reflects the evolution of birthstone lists, accommodating modern preferences for variety, durability, and personal style. This article explores the characteristics of each August birthstone, drawing upon established gemological and historical sources to provide a comprehensive overview for enthusiasts, collectors, and jewelry buyers.
Historical Evolution of the August Birthstones
The tradition of birthstones has evolved significantly over centuries, with the modern list being a product of both historical precedent and contemporary adaptation. The most widely recognized modern birthstone chart for August includes peridot and spinel, while sardonyx often appears as a traditional or alternative option. This multiplicity is not accidental; it is the result of deliberate updates by jewelry industry authorities to provide more choices and better reflect the available gem materials.
The National Association of Jewelers, now known as Jewelers of America, established the first official birthstone chart in the United States. This initial list was later revised, and in 2016, the American Gem Trade Association added spinel as an additional birthstone for August. This update was significant, as it provided those born in August with a wider array of colors and options beyond the traditional peridot. Sardonyx, a banded variety of chalcedony, has a long history as a gemstone, particularly valued for use in cameos, and is included on some birthstone lists for August. The presence of these three stones on various charts highlights the fluid nature of birthstone traditions, where both historical significance and modern market availability play a role in shaping the lists used by jewelers and consumers today.
Peridot: The Olive-Green Gem of the Sun
Peridot, the primary modern birthstone for August, is celebrated for its distinctive olive-green hue, a color attributed to its iron content. Unlike many gemstones that derive their color from trace elements, peridot’s color is a direct result of its chemical composition. It is a variety of the mineral olivine, and its gemological name is derived from the French word peritot, meaning "unclear" or "uncertain," though its identity as a gem has been well-established for millennia.
Geological Formation and Sources
Peridot is unique among gemstones as it is found in one type of rock: basalt. It forms deep within the Earth's mantle and is brought to the surface through volcanic activity. This origin makes it one of the few gems found in igneous rocks. Historically, peridot was mined on the island of Zabargad (also known as St. John’s Island) in the Red Sea, a source that was exploited for over 3,500 years. While this ancient source is now largely depleted, modern peridot is sourced from various locations worldwide, including the United States (Arizona, Hawaii), China, Myanmar, Pakistan, and Vietnam.
Gemological Properties
Peridot is valued for its good durability, though it requires careful handling in jewelry. Its key gemological properties are as follows:
| Property | Description |
|---|---|
| Chemical Formula | (Mg,Fe)₂SiO₄ |
| Crystal System | Orthorhombic |
| Hardness (Mohs Scale) | 6.5 to 7 |
| Refractive Index | 1.654 to 1.690 |
| Specific Gravity | 3.34 to 3.44 |
| Cleavage | Poor to none |
| Transparency | Transparent to translucent |
Peridot’s hardness of 6.5 to 7 means it is moderately durable but can be scratched by substances with a higher hardness, such as quartz or topaz. It has poor cleavage, which means it does not split easily along defined planes, but it can still be prone to chipping or breaking from a sharp blow. For this reason, peridot is often set in protective mountings, especially for rings and bracelets that experience frequent wear.
Symbolism and Lore
Peridot has been associated with the sun since ancient times. The Egyptians called it the "gem of the sun," believing it protected against evil spirits and was found in the settings of the famous Cleopatra’s emerald collection (though many of these "emeralds" were likely peridots). In medieval Europe, peridot was used to adorn churches and was believed to have healing properties, particularly for the eyes. Its bright, cheerful color is often linked to prosperity, growth, and renewal, making it a fitting symbol for the vibrant month of August.
Care and Cleaning
To maintain peridot’s brilliance, it should be cleaned with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaners, as the heat and vibrations can cause damage. Due to its moderate hardness, it is best stored separately from other jewelry to prevent scratches.
Spinel: The Durable and Colorful Alternative
Spinel joined the list of August birthstones in 2016, offering a wide range of colors and exceptional durability. It is often mistaken for other gems, such as ruby or sapphire, due to its similar appearance in red and blue varieties. However, spinel has its own distinct identity and is increasingly appreciated for its unique properties.
Geological Formation and Sources
Spinel forms in metamorphic rocks, often in association with minerals like corundum (ruby and sapphire) and chrysoberyl. It is found in placer deposits as well as in hard rock formations. Major sources of spinel include Myanmar (Burma), Sri Lanka, Vietnam, and Tanzania. The gem’s formation conditions allow for a variety of colors, depending on the presence of trace elements like iron, chromium, and cobalt.
Gemological Properties
Spinel is renowned for its excellent durability, making it suitable for all types of jewelry, including engagement rings. Its properties are summarized below:
| Property | Description |
|---|---|
| Chemical Formula | MgAl₂O₄ |
| Crystal System | Cubic |
| Hardness (Mohs Scale) | 8 |
| Refractive Index | 1.718 to 1.728 |
| Specific Gravity | 3.58 to 3.61 |
| Cleavage | Poor to none |
| Transparency | Transparent to translucent |
With a hardness of 8 on the Mohs scale, spinel is significantly harder than peridot and rivals many other popular gemstones. It is also tough, meaning it can withstand impacts without breaking. These properties make it an excellent choice for everyday jewelry. Spinel occurs in every color of the spectrum, with red and blue being particularly common and valuable. The red variety can closely resemble ruby, while the blue variety can mimic sapphire, but spinel’s single-refraction nature (it does not show pleochroism) can help gemologists distinguish it.
Symbolism and Lore
While spinel lacks the ancient lore of peridot, it has gained recognition as a symbol of revitalization and energy. Its vibrant colors are associated with passion (red) and tranquility (blue). In some modern interpretations, spinel is believed to promote physical and emotional healing, though these claims are not supported by historical tradition. Its inclusion as a birthstone is largely due to its beauty and durability rather than ancient legend.
Care and Cleaning
Spinel’s high hardness and lack of cleavage make it relatively easy to care for. It can be cleaned with warm, soapy water and a soft brush. Ultrasonic and steam cleaners are generally safe, but it is always advisable to consult a jeweler if the stone is set in a delicate mounting.
Sardonyx: The Banded Chalcedony
Sardonyx is a traditional birthstone for August, valued for its distinctive banding and historical use in cameos. It is a variety of chalcedony, which is a microcrystalline form of quartz, and is composed of alternating layers of sard (a reddish-brown chalcedony) and onyx (a black or white chalcedony). This banded structure creates striking patterns that have been prized by artisans for millennia.
Geological Formation and Sources
Sardonyx forms in volcanic cavities as a silica-rich solution precipitates layer by layer. The alternating colors are due to changes in the chemical composition of the solution during deposition. Sources of sardonyx include India, Brazil, Germany, and the United States. While not as widely mined as peridot or spinel, it remains a popular material for cabochons, beads, and cameos.
Gemological Properties
As a member of the quartz family, sardonyx has properties similar to other chalcedony varieties:
| Property | Description |
|---|---|
| Chemical Formula | SiO₂ |
| Crystal System | Trigonal (microcrystalline) |
| Hardness (Mohs Scale) | 7 |
| Refractive Index | 1.53 to 1.54 |
| Specific Gravity | 2.60 to 2.64 |
| Cleavage | None |
| Transparency | Opaque to translucent |
Sardonyx has a hardness of 7, making it durable enough for most jewelry applications. However, as an opaque stone, it is typically cut into cabochons (smooth, rounded domes) or beads rather than faceted gems. Its lack of cleavage and good toughness make it resistant to breakage, though it can still be scratched by harder materials.
Symbolism and Lore
Sardonyx has a rich history dating back to ancient Rome and Greece, where it was used for signet rings and cameos. It was believed to bring courage, protection, and good fortune to the wearer. In biblical tradition, sardonyx is one of the stones mentioned in the foundation of the New Jerusalem. Its banded appearance is often associated with stability and strength, making it a popular choice for talismans and amulets.
Care and Cleaning
Sardonyx can be cleaned with warm, soapy water and a soft cloth. Avoid harsh chemicals and ultrasonic cleaners, which may affect the stone’s polish or damage any treatments. As an opaque stone, it is less likely to show surface scratches than transparent gems, but care should still be taken to prevent abrasion.
Comparative Durability and Jewelry Applications
When selecting an August birthstone for jewelry, durability is a key consideration, especially for pieces worn daily like rings or bracelets. The three August birthstones differ significantly in their hardness and toughness, which influences their suitability for various settings.
Spinel stands out as the most durable of the trio, with a Mohs hardness of 8 and excellent toughness. It is suitable for any type of jewelry, including engagement rings, and can withstand decades of wear with proper care. Peridot, with a hardness of 6.5 to 7, is moderately durable but benefits from protective settings to avoid chipping or scratching. Sardonyx, with a hardness of 7, is also durable but is typically used in cabochon or bead forms, which are less prone to damage than faceted stones.
For those born in August, the choice of birthstone can be guided by personal preference for color, historical significance, or practical considerations. Peridot offers a unique olive-green hue with ancient Egyptian heritage, spinel provides a wide color palette and superior durability, and sardonyx delivers classic banding and cameo-cutting potential. Together, they represent a versatile and meaningful set of options for celebrating an August birthday.
Conclusion
The August birthstones—peridot, spinel, and sardonyx—offer a remarkable diversity in color, origin, and history. Peridot, with its solar associations and moderate durability, has been cherished since antiquity. Spinel, a modern addition, provides exceptional hardness and a rainbow of colors, making it ideal for contemporary jewelry. Sardonyx, a traditional stone, is valued for its banded patterns and long history in cameo carving. Each stone carries its own set of gemological properties, from peridot’s iron-induced green to spinel’s cubic crystal structure and sardonyx’s microcrystalline quartz composition. Understanding these characteristics allows gemstone enthusiasts and jewelry buyers to make informed choices, whether drawn to peridot’s ancient lore, spinel’s vibrant durability, or sardonyx’s artistic heritage. Together, they enrich the tradition of birthstones, providing meaningful and beautiful options for those born in the month of August.