August is unique in the calendar of birthstones, offering not one, but three distinct gemstones: peridot, sardonyx, and spinel. This multiplicity reflects a rich tapestry of history, geology, and evolving cultural preferences. While most months are associated with a single gem, August’s trio provides a diverse palette—from the vibrant green of peridot to the banded warmth of sardonyx and the brilliant sparkle of spinel. For those born in this summer month, the choice of a birthstone is not merely a matter of color but a connection to millennia of human tradition, from ancient religious artifacts to modern jewelry design.
The concept of birthstones as we understand it today is a relatively modern convention, standardized in the 20th century. However, its roots stretch back to the biblical Breastplate of Aaron, a sacred garment adorned with twelve gemstones representing the tribes of Israel. This ancient artifact is believed to have inspired the early association of gems with the zodiac and, later, the months of the year. The tradition evolved over centuries, influenced by regional availability, trade, and folklore. By the 18th century, a more formalized system began to emerge in Poland, where gem traders linked specific stones to each month. The final standardization occurred in 1912, when the American National Association of Jewelers established the modern birthstone list, which has since been updated to include additional stones for certain months, including August.
This article delves into the three official birthstones for August, exploring their unique histories, geological origins, gemological properties, and the symbolism they carry. We will examine why August has three birthstones, the historical journey of each gem, and the scientific facts that define them. By understanding these aspects, enthusiasts, buyers, and students of gemology can appreciate the depth and diversity that August’s birthstones offer.
The Historical Path to a Trio of Birthstones
The evolution of August’s birthstones is a story of tradition, adaptation, and industry response. The modern list, which includes peridot, sardonyx, and spinel, is the result of a long historical process that began with ancient texts and culminated in contemporary additions.
Ancient Origins and the Biblical Foundation
The tradition of associating specific gemstones with birth months can be traced back to the Breastplate of Aaron, as described in the Bible’s Book of Exodus. This sacred vestment featured twelve gemstones, each linked to one of the twelve tribes of Israel. Over time, these stones were also connected to the twelve signs of the zodiac and the twelve months of the year. This early framework laid the groundwork for what would become the birthstone tradition. In ancient Rome, gemstones were linked to mythological gods believed to rule over each month, further embedding gems into cultural and spiritual practices.
The Original Birthstone: Sardonyx
For August, the original birthstone was sardonyx, a banded variety of chalcedony. Its history as a birthstone dates back over 4,000 years, making it one of the oldest gems associated with the month. Ancient Greeks and Romans prized sardonyx for its use in cameos, amulets, and seals. They believed it symbolized strength, courage, and protection, attributes that made it a popular talisman for warriors and leaders. The stone’s durability and striking bands of red and brown were thought to enhance communication skills and bring victory in battle. This deep historical significance solidified sardonyx’s place as the primary August birthstone for centuries.
The Introduction of Peridot
While sardonyx held the historical title, peridot emerged as a popular alternative, particularly in more modern times. Peridot, a yellowish-green to greenish-yellow gem variety of the mineral olivine, was often confused with other gems like topaz and emerald throughout history. The Red Sea island of Topazios, a purported source of the name “topaz,” actually produced peridot. In Germany’s Cologne Cathedral, the Shrine of the Three Holy Kings is decorated with 200 carats of gems long believed to be emeralds but now identified as peridot. Some historians even speculate that Cleopatra’s famous emerald collection may have been peridot. The word “peridot” itself derives from the Arabic faridat, meaning gem. Valued in many ancient and medieval cultures, peridot was eventually recognized as the primary August birthstone, symbolizing abundance, protection, and positivity. Its vibrant green hue came to represent the lushness of summer.
The Modern Addition: Spinel
The most recent addition to August’s birthstone list is spinel. While spinel has been admired for centuries—often mistaken for rubies and sapphires due to its similar brilliance and color range—it was officially added to the modern birthstone list in 2016. The addition was driven by the jewelry industry’s desire to offer more variety and an affordable alternative to ruby, a gem with which red spinel was confused for centuries. Spinel’s inclusion acknowledges its beauty and historical value while providing August-born individuals with a wider array of choices, from fiery reds to deep blues and even pastel shades.
The question of why August has three birthstones is answered by this historical progression. As one source notes, “August has three birthstones due to historical tradition, gemstone availability, and the evolving preferences of the jewelry industry.” Sardonyx represents the ancient tradition, peridot signifies modern recognition and popularity, and spinel reflects contemporary updates to the birthstone list. This trio allows for a diverse expression of color, symbolism, and personal meaning, making August one of the most versatile months for gemstone selection.
Geological Formation and Global Sources
Each of August’s three birthstones forms under distinct geological conditions, contributing to their unique properties and appearances. Their sources are scattered across the globe, from volcanic landscapes to sedimentary deposits and even extraterrestrial origins.
Peridot: Born from Fire and Space
Peridot is the gem variety of the mineral olivine, with the chemical formula (Mg, Fe)₂SiO₄. Its formation is particularly remarkable, as it can be found in environments of extreme heat and pressure. One of the most fascinating sources of peridot is the Earth’s mantle, where it is brought to the surface by volcanic activity. Peridot crystals have been found in hardened lava, carried from deep within the mantle during eruptions. Even more extraordinary is its presence in meteorites—space rocks that have traveled from outer space to Earth. These extraterrestrial peridots provide a tangible link between our planet and the cosmos.
The primary sources of peridot are located in countries such as Egypt, Pakistan, Arizona (USA), and China. The ancient Egyptians mined peridot on the Red Sea island of Topazios, which is now known as Zabargad. This source was so significant that it influenced the historical confusion between peridot and topaz. In the United States, Arizona is a notable source, particularly from the San Carlos Apache Reservation, which produces large quantities of gem-quality peridot. The gem’s formation in these volcanic and meteoritic environments underscores its unique origin story.
Sardonyx: A Sedimentary Creation
Sardonyx is a banded variety of chalcedony, a microcrystalline form of quartz (SiO₂). It forms in sedimentary environments, where layers of silica-rich solutions deposit in cavities or voids, creating distinct bands of color. The bands in sardonyx typically alternate between shades of red (sard) and brown or black (onyx), resulting in a striking contrast. This banded appearance is a result of impurities and trace elements present during its formation.
Sardonyx is sourced from various regions, including India, Brazil, and the United States. In India, it is often found in the Deccan Plateau, while Brazilian deposits yield high-quality material. The United States also has sources, particularly in states like Oregon and Washington. The formation of sardonyx requires stable geological conditions over long periods, allowing for the gradual deposition of silica layers. Its durability and banding make it ideal for carving, which is why it has been used for cameos and seals since antiquity.
Spinel: Crystalline Beauty from Metamorphic Rocks
Spinel is a magnesium aluminum oxide (MgAl₂O₄) that forms in metamorphic rocks, particularly in contact zones where magnesium-rich rocks interact with aluminum-rich fluids. It can also be found in alluvial deposits, where weathering and erosion have transported crystals from their original host rocks. Spinel’s formation often occurs alongside other gems like ruby and sapphire, which is why it has been mistaken for them historically.
The most famous sources of spinel are Myanmar (Burma), Tajikistan, Sri Lanka, and Vietnam. Myanmar is particularly renowned for its vibrant red spinel, often associated with the legendary “Black Prince’s Ruby” in the British Crown Jewels, which is actually a spinel. Tajikistan’s Murghab region produces some of the finest blue and pink spinels. Sri Lanka and Vietnam are also significant sources, yielding a wide range of colors. The geological conditions in these regions—often involving high-pressure metamorphism—allow spinel to form in well-defined crystals with excellent clarity.
The table below summarizes the key sources for each August birthstone:
| Birthstone | Mineral Family | Primary Sources |
|---|---|---|
| Peridot | Olivine | Egypt, Pakistan, Arizona (USA), China |
| Sardonyx | Chalcedony (Quartz) | India, Brazil, United States (Oregon, Washington) |
| Spinel | Spinel Group | Myanmar, Tajikistan, Sri Lanka, Vietnam |
Gemological Properties
Understanding the gemological properties of peridot, sardonyx, and spinel is essential for identifying, valuing, and caring for these stones. Each has a distinct set of characteristics, from hardness and refractive index to color and clarity.
Peridot: The Green Olivine
Peridot is a relatively hard gemstone, with a Mohs hardness of 6.5 to 7. This makes it durable enough for everyday jewelry but requires care to avoid scratches from harder materials. Its chemical composition is (Mg, Fe)₂SiO₄, with iron being responsible for its characteristic green color. The color ranges from yellowish-green to greenish-yellow, and it remains consistently green under various lighting conditions, a rare trait among gemstones. Peridot has a refractive index of approximately 1.65 to 1.69 and a specific gravity of 3.34 to 3.48. It is typically found with good clarity, though inclusions are common and can affect value. Large peridots over 10 carats are rare and highly prized.
Sardonyx: The Banded Chalcedony
Sardonyx, as a variety of chalcedony, has a Mohs hardness of 6.5 to 7, similar to peridot. Its chemical composition is SiO₂, the same as all quartz varieties. The distinctive bands of sard (red-brown) and onyx (black or brown) are caused by impurities and layering during formation. Sardonyx has a refractive index of about 1.54 to 1.55 and a specific gravity of 2.60 to 2.64. It is typically opaque to translucent, and its value is influenced by the sharpness and contrast of its bands. Carved sardonyx, especially in cameos, commands higher prices due to the skill required in working with the stone.
Spinel: The Durable Oxide
Spinel is a relatively hard and durable gemstone, with a Mohs hardness of 8, making it more resistant to scratching than peridot or sardonyx. Its chemical formula is MgAl₂O₄, and it crystallizes in the cubic system. Spinel occurs in a wide array of colors, including red, blue, pink, purple, and black. The red variety is often compared to ruby, but spinel lacks the chromium that gives ruby its fluorescence. Its refractive index ranges from 1.71 to 1.73, and its specific gravity is 3.58 to 3.61. Spinel is known for its excellent clarity and brilliance, with few inclusions. The most valuable colors are vivid red and intense blue, with prices varying based on color saturation and size.
The following table compares key gemological properties:
| Property | Peridot | Sardonyx | Spinel |
|---|---|---|---|
| Mohs Hardness | 6.5–7 | 6.5–7 | 8 |
| Chemical Formula | (Mg, Fe)₂SiO₄ | SiO₂ | MgAl₂O₄ |
| Refractive Index | 1.65–1.69 | 1.54–1.55 | 1.71–1.73 |
| Specific Gravity | 3.34–3.48 | 2.60–2.64 | 3.58–3.61 |
| Color Range | Yellow-green to greenish-yellow | Banded red-brown and black | Wide range: red, blue, pink, etc. |
Symbolism and Metaphysical Beliefs
Throughout history, gemstones have been imbued with symbolic meanings and metaphysical powers. August’s birthstones each carry distinct associations, reflecting their unique properties and historical uses.
Peridot: Stone of the Sun and Protection
Peridot has long been associated with the sun, light, and protection. Ancient Egyptians believed it was a “gem of the sun,” capable of warding off evil spirits and bringing protection to the wearer. Its green color symbolizes growth, abundance, and renewal, aligning with the vitality of summer. In modern metaphysical beliefs, peridot is said to promote confidence, reduce stress, and attract prosperity. It is also linked to the heart chakra, fostering emotional balance and healing. For Leos, peridot is thought to enhance the traits of courage, loyalty, and leadership, mirroring the zodiac sign’s fiery nature.
Sardonyx: Stone of Strength and Communication
Sardonyx’s symbolism is rooted in its historical use as a talisman for warriors and leaders. Ancient Greeks and Romans believed it brought strength, courage, and protection in battle. It was also associated with enhanced communication skills, making it a popular stone for seals and amulets. In modern crystal healing, sardonyx is considered a grounding stone that promotes stability, discipline, and self-control. Its banded structure is thought to help balance energy and foster a sense of order. The stone’s red and black bands are symbolic of the balance between passion and restraint.
Spinel: Stone of Renewal and Vitality
Spinel’s symbolism is less documented historically, but its vibrant colors have led to associations with energy, renewal, and passion. Red spinel, in particular, is linked to vitality and courage, while blue spinel is associated with calm and clarity. As a relatively recent addition to the birthstone list, spinel’s metaphysical properties are more contemporary, often described as a stone of rejuvenation and inspiration. It is believed to help overcome lethargy and stimulate creativity. For August-born individuals, spinel offers a versatile symbol of summer’s warmth and dynamism.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone. The hardness and cleavage of each August birthstone dictate specific cleaning methods and handling precautions.
Peridot Care
With a Mohs hardness of 6.5 to 7, peridot is moderately durable but can be scratched by harder materials. It has no cleavage, making it less prone to breaking, but it is sensitive to rapid temperature changes, which can cause fracturing. To clean peridot, use warm soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as these can damage the stone. Store peridot jewelry separately to prevent scratches from other gems. For peridot set in jewelry, regular inspection of settings is recommended to ensure the stone remains secure.
Sardonyx Care
Sardonyx, with a hardness of 6.5 to 7, requires similar care to peridot. It is relatively durable but can be scratched. As a chalcedony variety, it is porous and can absorb chemicals, so it is best to avoid harsh cleaners and cosmetics. Clean sardonyx with mild soap, lukewarm water, and a soft cloth. Ultrasonic cleaners are generally safe for sardonyx, but steam cleaning should be avoided. For carved sardonyx pieces, gentle cleaning is crucial to preserve intricate details. Store separately to prevent damage.
Spinel Care
Spinel is the most durable of the three August birthstones, with a Mohs hardness of 8 and no cleavage. It is resistant to scratching and can withstand daily wear. Cleaning spinel is straightforward: use warm soapy water and a soft brush. Ultrasonic cleaners are safe for spinel, but steam cleaning should be used with caution due to potential inclusions. Spinel is stable under normal conditions and does not require special storage, but it is still advisable to keep it separate from harder stones like diamonds to avoid abrasion.
Conclusion
August’s three birthstones—peridot, sardonyx, and spinel—offer a remarkable diversity in color, history, and meaning. From the ancient origins of sardonyx, prized by Romans for its protective qualities, to the sunlit greens of peridot, a gem formed in Earth’s mantle and even in meteorites, and the brilliant versatility of spinel, recently added to the birthstone list, each stone tells a unique story. Their geological formations span volcanic landscapes, sedimentary layers, and metamorphic processes, sourcing from corners of the globe from Egypt to Myanmar. Gemologically, they vary in hardness, composition, and appearance, yet all share the durability and beauty that make them suitable for fine jewelry.
Symbolically, these stones embody the traits of August—abundance, strength, and vitality—aligning with the zodiac sign Leo and the summer season. For those born in August, the choice of a birthstone is a personal one, influenced by historical significance, aesthetic preference, and metaphysical beliefs. Whether selecting the verdant tranquility of peridot, the grounded strength of sardonyx, or the passionate sparkle of spinel, each gem serves as a meaningful connection to one’s birth month and the rich tapestry of human culture and natural history.