October Birthstone - Opal & Tourmaline
by Werneri Grundström
·10 minutes
October-born individuals are fortunate to claim two of the most visually captivating gemstones as their birthstones: the enigmatic opal and the versatile tourmaline. These gems stand out in the world of precious stones for their remarkable ability to showcase a spectrum of colors, albeit through different geological mechanisms.
What are October's birthstones?
October boasts two official birthstones:
- Opal
- Tourmaline
While both gems are celebrated for their polychromatic nature, they achieve this through distinct mineralogical properties.
Opal
Opals have captivated humanity for millennia with their otherworldly play of color. These gems seem to capture the essence of rainbows, auroras, and the iridescent feathers of exotic birds, all within a single stone. From ancient Roman emperors to modern jewelry enthusiasts, opals have maintained their allure as one of nature's most mesmerizing creations.
What is an opal?
Opal is a hydrated amorphous form of silica (SiO2·nH2O), containing 6% to 10% water. Its claim to fame is the mesmerizing "play-of-color" effect, scientifically termed opalescence. This optical phenomenon occurs due to the diffraction of light through a precise arrangement of silica spheres within the stone's structure.
Unlike most gemstones, opal is amorphous, meaning it lacks a crystalline structure. This unique characteristic contributes to its ability to create its signature color play, setting it apart in the world of precious stones.
Formation and sources
Opals form in the earth's crust where silica-rich water percolates through cracks and voids in rock. As water evaporates, it leaves behind silica deposits. Under specific conditions, these deposits arrange themselves into tightly packed spheres of varying sizes, typically 150 to 300 nanometers in diameter. This process can take thousands to millions of years, making each opal a testament to geological patience.
Major sources of opal include:
- Australia (particularly Lightning Ridge and Coober Pedy): Produces about 95% of the world's precious opals
- Ethiopia: A relatively new source, known for high-quality white and crystal opals
- Mexico: Famous for its fire opals
- Brazil: Produces a variety of opals, including rare black opals
- USA (Nevada and Oregon): Home to unique varieties like the Virgin Valley black opal
Each source imparts unique characteristics to its opals, from the deep, dark body tone of Lightning Ridge black opals to the neon orange of Mexican fire opals.
Types of opals
The world of opals is diverse, with each type offering its own charm:
-
Precious opal: Exhibits the classic play-of-color. Includes:
- Black opal: The most valuable, with a dark body tone enhancing color play
- White opal: Light body tone with vibrant play-of-color
- Crystal or water opal: Transparent to semitransparent with spectacular color flashes
- Common opal: Lacks play-of-color but can still be attractive. Often used in inlay work
- Fire opal: Known for its vibrant body color, often red, orange, or yellow. May or may not show play-of-color
- Boulder opal: Opal formed within ironstone matrix, often cut to show both opal and host rock
- Synthetic opal: Lab-created with the same chemical composition and optical properties as natural opal. Often used in more affordable jewelry
Physical and optical properties
Understanding opal's physical properties helps in both appreciating and caring for these delicate gems:
- Hardness: 5.5-6.5 on the Mohs scale, making it softer than many gemstones
- Specific gravity: 2.00-2.25, lighter than most precious stones
- Refractive index: 1.37-1.47, contributing to its unique optical effects
- Crystal system: Amorphous, unlike most crystalline gemstones
- Luster: Vitreous to resinous, adding to its visual appeal
- Transparency: Ranges from transparent to opaque, depending on variety
Opal care and maintenance
Due to their relative softness and water content, opals require special care:
- Avoid sudden temperature changes, which can cause thermal shock and cracking
- Clean with mild soap and lukewarm water, avoiding harsh chemicals
- Store separately in a soft cloth or pouch to prevent scratching
- Avoid ultrasonic cleaners and steam cleaning, which can damage the stone
- Keep away from prolonged exposure to strong light or heat, which can dry out the opal
With proper care, an opal can be a lifelong companion, its living colors a constant source of wonder and joy.
Tourmaline
Tourmaline, with its kaleidoscopic range of colors, stands as a testament to nature's artistic prowess. This gemstone family, more diverse in color than any other, has adorned royal crowns, graced museum collections, and become a favorite of modern designers. Its name, derived from the Sinhalese word "turmali," meaning "mixed colors," perfectly encapsulates its defining characteristic.
What is tourmaline?
Tourmaline is a boron silicate mineral with a complex chemical composition: XY3Z6(T6O18)(BO3)3V3W, where X, Y, Z, T, B, and W represent various elements. This complexity allows for a wide range of chemical substitutions, resulting in tourmaline's impressive color variety.
The tourmaline group includes several mineral species, but elbaite is the most common gem variety. Its ability to incorporate various elements into its crystal structure is the key to its remarkable color range, spanning virtually every hue in the rainbow.
Formation and sources
Tourmaline typically forms in pegmatites, which are coarse-grained igneous rocks, or in hydrothermal veins. The diverse chemical environment during formation contributes to its wide range of colors and compositions. Tourmaline crystals can grow in fascinating shapes, from slender needles to robust triangular prisms.
Major sources of tourmaline include:
- Brazil: Home to the famous Paraíba tourmaline and a wide variety of other colors
- Afghanistan: Known for producing fine red and green tourmalines
- USA (particularly Maine and California): Historic sources with a rich tourmaline mining heritage
- Pakistan: Yields exceptional pink and red tourmalines
- Mozambique: A significant producer of copper-bearing tourmalines similar to Paraíba
- Nigeria: Emerging source of various tourmaline colors
Each locality often produces tourmalines with characteristic colors or combinations, adding to the gem's allure for collectors and connoisseurs.
Tourmaline varieties
The tourmaline family is rich in varieties, each with its own charm:
-
Elbaite: The most common gem-quality tourmaline, including:
- Rubellite: Pink to red, often with a slight purple tinge
- Indicolite: Blue to blue-green, prized for its ocean-like hues
- Verdelite: Green, ranging from yellowish to bluish tones
- Paraíba: Neon blue-green, highly prized and among the most valuable tourmalines
- Schorl: Black tourmaline, the most common overall but rarely used in jewelry
- Dravite: Brown to yellow tourmaline, sometimes with a beautiful golden hue
- Liddicoatite: Rare calcium-rich tourmaline, often with complex color zoning
- Watermelon tourmaline: A bi-color or tri-color variety with pink center and green rim, resembling a slice of watermelon when cut in cross-section
Physical and optical properties
Tourmaline's physical properties contribute to its durability and versatility in jewelry:
- Hardness: 7-7.5 on the Mohs scale, making it suitable for everyday wear
- Specific gravity: 3.02-3.26, varying slightly with composition
- Refractive index: 1.624-1.644, giving it a bright luster
- Crystal system: Trigonal, often forming in distinctive elongated crystals
- Luster: Vitreous, adding to its visual appeal
- Transparency: Ranges from transparent to opaque, with some specimens showing chatoyancy or cat's-eye effect
Tourmaline care and maintenance
While more durable than many gemstones, tourmaline still benefits from proper care:
- Clean with warm, soapy water and a soft brush, avoiding harsh chemicals
- Avoid steam and ultrasonic cleaners, which can potentially damage the stone
- Store separately to prevent scratching from harder gemstones
- Avoid exposure to extreme heat, which can alter color in some tourmalines
- Remove before vigorous physical activities to prevent accidental damage
An interesting feature of tourmaline is its pyroelectric and piezoelectric properties. When heated or pressurized, tourmaline can generate a small electrical charge, a characteristic that has led to its use in various scientific instruments.
Opal vs. Tourmaline: Choosing Your October Birthstone
October-born individuals are blessed with a choice between two extraordinary gemstones: the enigmatic opal and the vibrant tourmaline. Each stone offers its own unique allure, making the selection a matter of personal preference and lifestyle considerations.
The Color Play
Opals are renowned for their mesmerizing play-of-color, a phenomenon that creates a shifting rainbow effect within the stone. This captivating display can include every color of the spectrum, from fiery reds to cool blues, all shimmering and changing with movement and light. The base color of opals can range from milky white to midnight black, with the latter typically commanding higher prices due to the striking contrast it provides to the play-of-color.
Tourmalines, on the other hand, offer a different kind of color magic. Unlike opals, tourmalines typically display solid, rich hues. The variety of colors available in tourmaline is staggering - from deep reds and pinks to vivid greens and blues, and even multi-colored specimens. Perhaps the most coveted variety is the Paraíba tourmaline, known for its intense neon blue to green color that seems to glow from within.
Durability and Care
When it comes to durability, tourmalines have an edge over opals. With a hardness of 7 to 7.5 on the Mohs scale, tourmalines are well-suited for everyday wear in all types of jewelry. Opals, being softer at 5.5 to 6.5, require more careful handling and are more susceptible to scratching or chipping. This makes tourmalines a practical choice for those who lead active lifestyles or prefer low-maintenance jewelry.
Care requirements differ between these two gems as well. Opals contain water in their structure and can be sensitive to extreme temperatures or dry conditions. They benefit from gentle cleaning with mild soap and water, and should be stored carefully to prevent scratching. Tourmalines are generally easier to care for, though they should still be protected from harsh chemicals and extreme heat.
Value and Rarity
The value and rarity of both stones can vary widely. Fine quality opals, particularly black opals with vivid play-of-color, can be extremely valuable.
Similarly, certain tourmaline varieties like the Paraíba can command very high prices. However, both stones also offer more affordable options, making them accessible to a wide range of buyers.
Symbolic Meanings
Symbolically, opals have long been associated with creativity, spontaneity, and emotional expression. Their ever-changing play of color is seen as a reflection of the wearer's moods and feelings.
Tourmalines, with their variety of colors, have accumulated various meanings over time. Green tourmalines are often linked to growth and balance, pink to compassion, and black to protection.
Making Your Choice
When choosing between opal and tourmaline, consider your personal style, lifestyle, and the type of jewelry you prefer. If you're drawn to the mysterious and ever-changing, an opal might be your perfect match. If you prefer bold, defined colors and value versatility in your jewelry, tourmaline could be the ideal choice.
Ultimately, both opal and tourmaline offer unique beauty as October birthstones. Whether you're captivated by the ethereal play of light in an opal or the rich, vibrant hues of tourmaline, you'll be wearing a piece of nature's artistry that connects you to the month of October. Consider trying on jewelry featuring both stones to see which resonates more with you personally. Remember, there's no wrong choice - both gems have their own special way of capturing the beauty and diversity of the natural world.
The Mystical Properties and Cultural Significance of October Birthstones
Opal: The Stone of Inspiration
Throughout history, opal has captivated imaginations with its fiery play of colors. In the Roman Empire, it was known as "Cupid Paederos," meaning a child as beautiful as love, symbolizing hope, purity, and luck. This reverence for opal extended to other ancient cultures as well.
Arabic lore painted a dramatic picture of opal's origin:
- Believed to fall from heaven in flashes of lightning
- Revered as a protective stone due to its celestial connections
In Medieval Europe, opal gained a reputation that mixed marvel with mystery:
- Known as "Ophthalmius" or eye stone
- Thought to benefit eyesight
- Believed to grant the power of invisibility
The cultural significance of opal runs deep in many societies. Greek tradition associated it with prophetic powers, believing it could provide foresight and protection from disease. Perhaps the most poetic origin story comes from Australian Aboriginal Dreamtime, which tells of the Creator's footsteps sparking the opal's rainbow colors as a message of peace to humanity.
In modern crystal healing practices, opal is attributed with various emotional and spiritual properties:
- Intensifying emotional states
- Enhancing self-worth and confidence
- Aiding in releasing anger and claiming one's true self
Tourmaline: Enhances Mental Clarity
Tourmaline, with its vast spectrum of colors, has accumulated a rich tapestry of cultural significance. Its very name, derived from the Sinhalese "turmali" meaning "mixed colors," speaks to its defining characteristic. An Egyptian legend beautifully captures this essence, describing tourmaline as passing through a rainbow while rising from the Earth's center, collecting all colors in the process.
Different cultures have ascribed various meanings to tourmaline's colors. Native American traditions, for instance, attribute specific properties to each hue:
- Black: Protection from negative energies
- Green: Courage, strength, stamina
- Pink: Love, compassion, gentleness
In African traditions, shamans prized tourmaline for its perceived ability to connect with the spiritual world, believing it could awaken the senses and provide insight. During the European Renaissance, the stone became associated with enlightenment, sought after by philosophers and artists as a source of inspiration.
China's appreciation for tourmaline, particularly the pink variety, is well-documented. It was often carved into intricate decorative items, with the Empress Dowager Cixi of the Qing Dynasty famously cherishing pink tourmaline to the extent that she was buried on a tourmaline pillow.
Modern crystal healing practices attribute a range of properties to tourmaline:
- Considered a stone of reconciliation
- Believed to foster compassion and cool-headedness
- Thought to attract money, healing, and friendship
Different colors of tourmaline are associated with various chakras, making it a versatile stone in energy healing practices.
Contemporary Cultural Impact
Both opal and tourmaline continue to hold significant places in various cultures today. Opal, as Australia's national gemstone, plays a crucial role in the country's identity and economy. The mining and trading of opals have become integral parts of Australian culture, particularly in rural areas.
In the world of fashion and jewelry design, these October birthstones are celebrated for their unique qualities:
- Opal's play-of-color is showcased through innovative cuts and settings
- Tourmaline's range of colors allows for versatile and bold designs
The mystical properties attributed to these stones have also found a place in contemporary spiritual and wellness practices. Many people choose to wear opal or tourmaline jewelry not just for its beauty, but also for its perceived energetic and healing properties.
The Bottom Line
October's birthstones, opal and tourmaline, offer a stunning array of colors and unique properties. Whether you choose the ethereal play-of-color in opals or the vibrant hues of tourmaline, these gems provide beautiful options for jewelry and continue to captivate gem enthusiasts worldwide.
