August, heralded by the warmth of late summer and the promise of autumn, is among only a few months represented by multiple birthstones. Three gemstones — Peridot, Spinel, and Sardonyx — share the distinction of being associated with those born in August. Each possesses a unique color palette and an equally fascinating history that spans cultures, centuries, and jewelry traditions. While Peridot is widely regarded as the primary August birthstone and is celebrated for its vibrant green hue, the vivid reds, purples, and blues of Spinel have recently captured collectors' attention as a more affordable alternative to high-cost gems like ruby. Meanwhile, Sardonyx, with its banded appearance and historical significance in seal stones and cameos, offers a more antiquated, yet enduring presence in contemporary settings.
This article explores the historical evolution, geological properties, cultural symbolism, and care instructions of August’s three official birthstones, drawing exclusively from the provided sources. By understanding the attributes that define these stones, both professionals and collectors alike can better appreciate their role in jewelry design, their symbolic meanings, and the scientific processes that contribute to their beauty and diversity.
History and Lore: From Ancient Amulets to Modern Jewelry
The Origins of Peridot as an August Birthstone
Peridot has a history that stretches back into antiquity, with early references found in Egyptian and Roman cultures. Known as the “gem of the sun,” Peridot was believed by the ancient Egyptians to protect against nightmares and evil spirits, making it a favored adornment in both amulets and jewelry. This belief is further supported by Hawaiian mythology, which credits the creation of Peridot to Pele, the goddess of fire and volcanoes, suggesting that the gem symbolizes renewal and the fiery origins of its formation.
Peridot's recognition as the primary August birthstone came through its prominence in historical jewelry traditions. It was widely used in seal stones and signet rings, particularly in civilizations that valued both its aesthetic and symbolic properties. While earlier iterations of the August birthstone jewelry often included sardonyx, peridot emerged as a dominant option in the modern era, a shift that reflects both its rarity in high-quality specimens and its increasing appeal in contemporary jewelry markets.
The Evolving Story of Sardonyx
Sardonyx, a composite of sard (reddish-brown chalcedony) and onyx (banded, dark-colored chalcedony), carries one of the longest traditions of any August birthstone. The ancient Romans and Greeks prized sardonyx for its suitability in carving and for its symbolic associations with strength, victory, and protection. Romans favored it for signet rings and seals due to its non-stick surface, which made it ideal for stamping wax.
While sardonyx has been historically considered the original June or August birthstone, modern birthstone lists have largely shifted to peridot and spinel as the primary and secondary August stones. However, the historical symbolism of sardonyx — particularly its use in amulets and intaglios as protective talismans — remains well-documented.
The Modern Resurgence of Spinel
Spinel, though far less commonly recognized than ruby or sapphire, has been mistaken for both due to its striking colors and high refractive index. Despite its long history in royal museums and jewelry collections, including the infamous Tavernier Blue, which was recently reclassified as a spinel, this gemstone remained in the shadow of its more well-known counterparts for many years.
The modern revival of spinel began in earnest with the 2007 discovery in Tanzania of vivid pink and red spinel crystals, which sparked renewed interest among collectors and jewelry designers. Spinel has since been officially recognized as a primary August birthstone, adding a rich array of colors to the month’s birthstone selection. The inclusion of spinel allows for a more diverse and affordable August birthstone jewelry market, bringing vibrant hues like red, blue, and purple into the scope of meaningful gifts.
Geological Formation and Sources
How and Where Peridot is Formed
Peridot forms in magma and volcanic environments, typically under high temperatures and pressure. It is a magnesium iron silicate (chemical formula: Mg₁₋ₓFeₓSiO₄), and its characteristic green color comes from the presence of iron, which replaces magnesium in the crystal lattice. The higher the iron content, the deeper the green hue.
The most reputable sources for peridot include:
- Zabargad Island (St. John’s Island) in the Red Sea, historically a major contributor to ancient Egyptian gemstones.
- Arizona (USA), where green peridot is mined as "Arizona peridot."
- Madagascar, noted for producing high-quality specimens in a range of green shades.
Spinel’s Diverse Geographical and Geological History
Spinel is a mineral that forms in a variety of geological settings, including metamorphic and igneous rocks. It is composed of an oxide mineral compound (typically MgAl₂O₄, with color variations due to trace elements like chromium or iron).
Historically found in all major continents, spinel’s global sources include:
- Tanzania, where the 2007 discovery of vibrant red and pink spinels brought renewed attention.
- Brazil, known for producing deep red and hot pink spinels.
- Vietnam, famous for cobalt-blue spinels.
These deposits are particularly significant for offering color-rich, affordable alternatives to ruby and sapphire.
Spinel is typically a hard and durable stone, rated 8 on the Mohs scale, making it well-suited for use in earrings, pendants, and rings.
The Composition and Formation of Sardonyx
Sardonyx is a banded variant of chalcedony, a form of microcrystalline quartz. It forms in cavities and veins within rocks, where alternating layers of iron-bearing and iron-free silica crystallize. The reddish sard layers derive their hue from iron oxide, while the onyx layers remain white or black.
Sardonyx is typically sourced from:
- India, particularly in Rajasthan, where it has been a major supplier for centuries.
- Brazil, a modern alternative that produces vibrant contrasts between the sard and onyx layers.
Although its formation is less studied as a standalone gemstone compared to peridot or spinel, sardonyx’s durability and ease of carving have made it a favored stone for cameos, seals, and signet rings in both ancient and modern jewelry.
Gemological Properties: Color, Clarity, and Composition
Peridot
- Hardness: 6.5 to 7 on the Mohs scale. It is moderately hard but susceptible to scratches and may lack structural integrity in certain faceted cuts due to directional cleavage.
- Color: Ranges from a light yellow-green to a rich olive green, varying depending on the iron content. Peridot never shows the classic red or blue hues.
- Luminescence and Lighting Response: Peridot is particularly striking under natural daylight due to its high refractive index and vibrant transparency.
- Chemical Composition: Magnesium iron silicate, (Mg,Fe)₂SiO₄.
- Origin of Color: The green color is due to iron present in the crystal lattice. The more iron, the deeper the green.
- Common Cuts: Round, oval, and cushion cuts are most popular for maximizing its color.
- Carat Range: While peridot is fairly common, exceptional green peridot in larger sizes can be rare and valuable.
Spinel
- Hardness: 8 on the Mohs scale, making it a highly durable and versatile gem.
- Color Range: Spinel is one of the most color-variety-rich gemstones, typically found in red, pink, purple, blue, and black. Some even show multi-colored internal zoning.
- Luminescence and Lighting Response: Spinel is renowned for its bright luster and luminescence under light, particularly in the red and violet shades.
- Chemical Composition: A cubic oxide compound, typically MgAl₂O₄, with color variation from trace elements.
- Common Cuts: Round, cushion, and oval cuts are most common. The 2007 Tanzania spinels often come with a brilliant cut to highlight their vivid hue.
- Exceptional Pieces: Deep red spinels, known as “Burmese reds”, are among the most prized despite being less expensive than red sapphires or rubies.
Sardonyx
- Hardness: 6.5 to 7 on the Mohs scale. While not as hard as spinel or corundum, sardonyx remains fairly durable and widely used in fine jewelry.
- Color Range: Varied color bands, especially reddish sard and white or black onyx layers. The banding depends entirely on the geological impurities present during formation.
- Luminescence and Lighting Response: Sardonyx tends to absorb rather than refract light, giving it a matte to semi-glossy finish rather than the sparkly nature of peridot or spinel.
- Chemical Composition: Cryptocrystalline quartz, with iron oxide providing the red tones.
- Common Cuts: Sardonyx is most often cut as cabochons or beads to showcase its banding. Cameos and intaglios are classic treatments.
- Durability Considerations: While relatively hard, it is a porous material, requiring careful handling and proper care to avoid damage from abrasive cleaners or scratches.
Symbolism and Metaphysical Beliefs
Peridot: The Stone of Change and Positivity
Peridot has long been regarded as a stone of positivity and renewal, especially among cultures that associate green with fertility and life. In Egypt, it was thought to repel misfortune and promote good dreams, making it a popular stone for those seeking protection during the night.
Modern metaphysical traditions still attribute powerful properties to peridot. It is believed to:
- Encourage emotional balance and spiritual wisdom
- Assist in the release of fear and trauma
- Symbolize abundance and prosperity, particularly when worn or placed in spaces of financial or personal growth
These attributes may explain the growing popularity of peridot in self-care and meditation circles, where it is used as a vibrational cleanser for clearing negative energy.
Spinel: The Stone of Passion and Clarity
Spinel has a more varied symbolism depending on its color. Red spinel, for example, is often compared to gem tourmaline and ruby in its energetic expression but is believed to carry a more gentle, balanced form of passion and desire. Purple and blue spinels, on the other hand, are associated with spiritual insight and calming energies.
Some of the modern metaphysical meanings of spinel include:
- Promoting inner strength and confidence, especially in red and orange tones
- Enhancing perception and emotional clarity, particularly in the pink and purple hues
- Balancing and harmonizing emotions and thoughts
Spinel’s association with kings and royalty in historical collections has also contributed to its modern symbolism as a stone of regality and inner nobility.
Sardonyx: The Stone of Protection and Practicality
Historically worn as a protective talisman in battle by Roman and Greek warriors, sardonyx is associated with strength, protection, and clear communication. Its banding is thought to represent the balance between fire (red sard) and air (white or black onyx), promoting courage and strategic thinking.
Metaphysical uses for sardonyx include:
- Stimulating willpower and confidence
- Stabilizing emotions and reducing anxiety
- Encouraging long-lasting relationships and communication
In contemporary practices, sardonyx is especially valued in meditation and business settings, where clarity and calmness are essential.
Care and Cleaning: Preserving the Luster of August’s Birthstones
Each August birthstone requires specific care due to its individual hardness, porosity, and reactivity to light and chemicals. Proper maintenance ensures that the gems retain their beauty and durability over time.
Peridot
Peridot is relatively soft compared to other gemstones, with a Mohs hardness of 6.5 to 7. It is also prone to cleavage and chipping, especially if struck at sharp angles.
- Cleaning: Use mild soapy water and a soft cloth. Avoid ultrasonic and steam cleaners, as the vibration can cause fractures or cleavage.
- Storage: Store peridot separately from harder gemstones to prevent scratching.
- Exposure to Heat: Peridot is relatively heat-resistant, but prolonged exposure to high heat can dull its color.
- Chemical Sensitivity: While it has moderate stability to everyday chemicals, avoid contact with harsh solvents or perfumes.
Spinel
Spinel has exceptional durability and is rated 8 on the Mohs scale, making it suitable for daily wear in rings and earrings.
- Cleaning: Safe for ultrasonic and steam cleaning. If the gem has undisclosed fractures, it is advisable to use warm soapy water instead.
- Heat and Light Exposure: Spinel is stable under light and heat, but deep red and orange spinels may fade under prolonged sun exposure.
- Chemical Stability: Spinel is highly resistant to chemicals, making it a low-maintenance gemstone for most jewelry settings.
Sardonyx
Sardonyx is fairly durable (Mohs hardness of 6.5 to 7) but is more porous than other gemstones, making it more susceptible to scratches and staining.
- Cleaning: Clean using mild soapy water and a soft brush. Avoid ultrasonic cleaners unless recommended by the jeweler.
- Heat and Light Exposure: Minimal risk of fading, but high heat can cause discoloration in red sardonyx.
- Chemical Sensitivity: Due to its porous nature, it is recommended to avoid harsh chemicals to prevent staining or etching.
Conclusion
The August birthstone selection — peridot, spinel, and sardonyx — represents a rich tapestry of geological diversity, historical significance, and symbolic meaning. From the radiant green glow of peridot to the fiery red hues of spinel, and the elegant banding of sardonyx, each stone offers a unique expression of beauty, strength, and clarity.
Peridot’s resurgence in design, especially in statement pieces and affordable yet vibrant jewelry, aligns with a modern appreciation for colorful, energetic gemstones. Spinel, with its stunning range of colors and recent validation as a birthstone, provides an accessible alternative to rare or costly gems. Sardonyx, though less prominent in contemporary settings, carries a timeless elegance and historical weight that makes it a compelling choice for those wishing to honor tradition.
When selecting or caring for August birthstone jewelry, it is crucial to consider each gem’s individual properties and requirements, ensuring that the chosen stones are well-matched to their intended wear and lifestyle. Whether gifted or self-selected, August’s birthstones serve not only as adornments but as keepers of color, history, and personal significance, making them a fitting tribute to the month and its bearers.