August marks one of the most unique months in the birthstone calendar, with not one, but three officially recognized gemstones: Peridot, Spinel, and Sardonyx. This diversity speaks to the richness of August’s gemstone heritage and allows for an intriguing journey through both the physical and symbolic facets of these stones. Whether it's the vibrant green of Peridot, the fiery brilliance of Spinel, or the banded strength of Sardonyx, each stone offers a distinct allure. This article presents an exhaustive overview of the August birthstones, emphasizing their gemological properties, historical usage, cultural symbolism, and practical considerations for ownership and care.
History and Lore
Sardonyx: The Original August Birthstone
Sardonyx holds the distinction of being the oldest recorded August birthstone, with a history stretching back over 4,000 years (Source 2). Ancient civilizations, particularly the Romans and Egyptians, revered this banded onyx. Its striations of reddish-brown and white created a striking appearance, often symbolizing both strength and protection. Roman soldiers were known to wear Sardonyx amulets for courage and luck in battle (Source 3). It also appeared frequently in seal carvings and cameos, especially in engraved intaglios that were used as imperial insignias (Source 1).
Despite its prominence, Sardonyx was eventually overshadowed and confused with green-hued Peridot. In fact, the distinction between the two was not always clear, and it took time and expertise to differentiate them. Still, Sardonyx retained a steady, albeit lesser, presence in jewelry and gemstone lore across the ages.
Peridot: The Green Gem of the Sun
Peridot, the most widely recognized and popular of the August birthstones, has a distinctive yellowish-green to greenish-yellow hue. Known throughout history for its association with solar energy and healing, it was called “the gem of the sun” by the ancient Egyptians. As much as it is treasured today, its history is filled with tales of misidentification and mystery.
For example, the Shrine of the Three Holy Kings in Cologne Cathedral was once believed to include emeralds among its 200 carats of gemstones, but these were in fact Peridots. Source 2 notes that even Cleopatra’s famed emerald collection may have been largely composed of Peridot, suggesting that confusion existed between green gems long before modern gemology clarified their identities.
Peridot’s historical association with positive energy and optimism has never waned. It continues to be linked with fresh beginnings, emotional healing, and protection—particularly from negativity. Historically, it was also used in jewelry for both the nobility and commoners, which testifies to its beauty and availability.
Spinel: The Recently Eclipsed Jewel
Spinel is the youngest gemstone to be officially associated with August, having been added in 2016 as a reflection of modern taste and a way to distinguish it from Ruby, which it resembles closely in appearance (Source 1). Though underappreciated for centuries, Spinel was often misattributed as a Ruby when found in deep red tones, and even when discovered in blue, pink, or even colorless forms, it did not gain the recognition it deserved.
The Rediscovery of Spinel in modern times has been a revelation for the gemological world. Its brilliant clarity and strong refractive index rival the best of the ruby family. With its wide range of colors, it’s increasingly seen as a versatile and ethically desirable alternative to rarer, more expensive stones. In today’s jewelry market, Spinel is becoming a favorite among high-style designers who appreciate both its beauty and durability.
The addition of Spinel to the August birthstone list is a nod to the evolving standards of the gemology community and the desire to recognize new stones as they gain prominence in fashion and science.
Geological Formation and Sources
Peridot
Peridot is formed deep within the Earth's mantle, where extreme heat and pressure cause magma to cool, solidifying the olivine crystal. These crystals are brought to the surface through volcanic processes, often embedded in hardened lava. In some cases, Peridot can be found in meteorites, making it one of the rarest earth minerals, and possibly the only gemstone formed beyond Earth itself (Source 2).
Peridot is mined in several regions around the world, including:
- Zabargad Island (Red Sea): One of the most famous and historic sources.
- Arizona, USA: Notable in meteorites such as the Barringer Meteor Crater.
- Brazil, China, and Australia: Important modern sources.
Its availability in both massive and faceted forms made it a popular jewelry gem across civilizations, with the Egyptians and Romans using it extensively for ornamental and protective purposes.
Spinel
Spinel is a silicate mineral with a general chemical formula MgAl₂O₄, and it forms under similar high-pressure conditions as corundum (the mineral group of Rubies and Sapphires). It is frequently found in mafic and ultra-mafic igneous rocks, as well as in metamorphic deposits (Source 4). Unlike Peridot, which is a silicate of olivine, Spinels crystallize in the isometric system, which gives them durable hardness and a glassy luster.
Spinel is found in locations such as:
- Maharashtra and Andhra Pradesh, India
- Sri Lanka—particularly for fine blue and red stones
- Myanmar, for rich rubicel and pink tones
- Madagascar, for a wide range of colors including inky black and vivid red
The rediscovery of Spinels in royal and historical collections has led to some well-documented repurcussions, such as the Kuh-i-No Spinel, reclassified in recent years. This discovery highlights the increasing appreciation and re-evaluation of Spinels in both the collected and wearable gem market.
Sardonyx
Sardonyx is a variety of chalcedony, a sedimentary rock that is actually a form of microcrystalline quartz. Its banded patterns result from alternating layers of sard (a reddish-brown chalcedony) and white onyx forming under hydrothermal and sedimentary environments. These bands develop slowly over millions of years, influenced by the presence of iron and silica in the deposit.
Historically, the best sources of Sardonyx were:
- Italy (particularly Sardinia), which gives the stone its name
- India, where much of the Roman demand was met through trade routes
Today, modern sources include:
- India and Brazil, where quality material is still mined for jewelry and ornamental use
- Iceland, known for unique deposits of banded agate—which can resemble Sardonyx
Sardonyx is notorious for being easily confused with other banded stones, such as onyx and agate, which is why proper testing and authentication is necessary, especially for historical or heirloom pieces.
Gemological Properties
| Gemstone | Color | Hardness (Mohs) | Chemical Composition | Refractive Index | Cleavage | Transparency |
|---|---|---|---|---|---|---|
| Peridot | Yellowish green to lime | 6.5 – 7.0 | (Mg, Fe)₂SiO₄ (Olivine) | 1.653 – 1.689 | Perfect | Transparent |
| Spinel | Red, blue, pink, black | 8.0 | MgAl₂O₄ | 1.718 – 1.725 | Indistinct | Transparent |
| Sardonyx | Reddish-brown & white | 6.5 – 7.0 | Chalcedony (SiO₂) + iron oxide | 1.48 to 1.53 | None | Translucent to Opaque |
Peridot’s Distinctive Traits
Peridot is known for its only-green coloration, making it one of the few gemstones that occur exclusively in a single hue (excluding synthetic imitations). Its high refractive index gives it a fiery luster, especially in lighter green varieties, where pleonasm (split light beams) is often visible.
Peridot is also known to be piezoelectric, meaning it can generate an electric charge when subjected to mechanical stress—a rare property among gemstones. This scientific detail enhances its mystique and makes it a subject of ongoing mineralogical interest.
Spinel’s Versatility
Spinel comes in an extremely wide range of colors, from intense reds and pinks to deep blues and inky blacks. The stone’s hardness (8.0 on the Mohs scale) and lustrous clarity make it ideal for everyday wear, especially in high-end jewelry. Unlike rubies and sapphires, which are often heat-treated or irradiated, fine Spinels are typically found in their natural condition, which adds to their desirability in the ethical and conflict-free gemstone movement.
Sardonyx: A Band of Protection
Sardonyx, as a form of quartz, has a good to moderate hardness (6.5–7.0) and no cleavage, which allows it to be carved and shaped easily. Its translucent to opaque texture makes it ideal for cameos, intaglios, and beads, and has historically made it a favorite for both jewelry and symbolic amulets.
Symbolism and Metaphysical Beliefs
Peridot – The Light of Sun and Spirit
In addition to its physical beauty, Peridot has long been associated with positive energy and protection. Many ancient cultures believed that Peridot possessed the power to repel nightmares and negative energies, making it a revered stone in protective amulets and charms.
In modern metaphysical traditions, Peridot is closely tied to heart and solar plexus chakras, and is considered ideal for emotional healing, promoting gratitude, and releasing fears or burdens. It is also thought to enhance balance in relationships and provide clarity in decision-making, which contributes to its popularity both as a jewelry and healing gemstone.
Spinel – A Stone of Emotional and Physical Vitality
Spinel is revered in modern crystal healing for its revitalizing energy. It is considered a stone of strength, helping warriors and travelers to maintain courage and presence in challenging situations (Source 4). Some even think it can revive the body and mind after illness or exhaustion.
In terms of emotional support, Spinel is particularly valued for promoting confidence and passion, and for invoking a sense of joy and vitality in daily life. High-quality blue and red Spinels are also associated with planetary energies of Saturn and Mars, making them vibrant choices for those interested in astrological healing (Source 4).
Sardonyx – A Symbol of Steadiness and Communication
Among the three, Sardonyx is most associated with grounding and protection. It is often used in rituals and talismans for courage and to enhance communication, especially in leadership or public speaking. In ancient Roman culture, Sardonyx was believed to confer victory in battle and protection from malevolent forces.
Today, Sardonyx is still seen as a stone for those who need to stay grounded or reconnect with their personal power. It is also often recommended for people with a tendency to speak impulsively, helping to cultivate patience and thoughtful expression.
Care and Cleaning
Peridot
Due to its lower hardness (6.5–7), Peridot should be handled carefully, especially when set in rings where it can be subjected to abrasion and impact. It is best cleaned with warm, soapy water and a soft brush or microfiber cloth. Avoid steam cleaning, ultrasonic cleaners, and exposure to acids or harsh chemicals, which can damage or dull its surface.
Peridot is also sensitive to heat, so it’s not recommended to wear it during high-temperature activities or near open flames.
Spinel
Spinel is much harder (8.0 on the Mohs scale) and resists scratching and abrasion, making it ideal for daily wear. It can be cleaned using standard methods for high-hardness gems. This includes soapy water, a mild ultrasonic cleaner, and a soft cloth or brush.
Spinel is not known to be sensitive to light or heat, making it very versatile for use in rings, pendants, and bracelets.
Sardonyx
As a quartz-based stone with no cleavage, Sardonyx is fairly durable and easy to clean. However, because it is less hard than Spinel and slightly softer than Peridot (6.5–7), it should be stored separately from harder materials to avoid scratches.
Cleaning Sardonyx can be done with mild soap and water, and gently rinsing it under lukewarm water. Avoid using harsh abrasives or acidic solutions, and never expose it to high-heat settings.
Conclusion
The August birthstones—Peridot, Spinel, and Sardonyx—offer a trio of unique geological identities, rich histories, and symbolic meanings. From Peridot's origins in volcanic fire and solar energy, to Spinel’s recent rise in gemological recognition, and Sardonyx’s ancient standing as a protective banded stone, the diversity of August’s birthstone legacy is truly remarkable.
Each gem has found a distinct place in both science and spiritual belief, and their increasing use in modern jewelry reflects a growing appreciation for authentic, meaningful stones. Whether you're drawn to Peridot's healing green, Spinel's rare vibrancy, or Sardonyx’s grounding bands, choosing an August birthstone is more than just an aesthetic decision—it is a connection to history, beauty, and the natural world.
For gemstone enthusiasts, jewelers, or collectors, understanding these stones in depth offers not only practical insight but also a deeper appreciation for the symbolic and physical treasures of the Earth.