October is one of the most fascinating months in the world of birthstones, boasting two official gemstones: opal and tourmaline. Both are renowned for their diverse color palettes and unique optical properties, making them stand out in the world of gemstones. While opal has long been associated with October, the inclusion of tourmaline—particularly pink tourmaline—began in the early 20th century. Together, these stones encapsulate the month’s symbolic themes of transition, transformation, and the culmination of seasonal change.
This article explores the rich history, geological properties, cultural symbolism, and practical care of both opal and tourmaline. Drawing from authoritative sources, we will uncover the reasons these gemstones were chosen for October and how they continue to inspire jewelry designers and gem lovers alike.
History and Lore of October Birthstones
The tradition of associating gemstones with the months of the year dates back centuries, with early lists influenced by biblical references and ancient beliefs. October’s original birthstone, according to these early systems, was beryl or aquamarine. However, this changed over time, and opal eventually became the primary October birthstone.
Opal has long been a gem of intrigue and mystique. Its name is thought to derive from the Sanskrit word upala, meaning "precious stone," which was later transformed into opalus in ancient Rome. Opal is known for its "play-of-color," a phenomenon where the gem displays a shifting array of hues depending on the angle of light. This effect fascinated ancient cultures, who attributed magical and prophetic properties to the stone.
The ancient Greeks believed opal granted the gift of prophecy and protected against disease. The Bedouins, on the other hand, thought it contained lightning from thunderstorms. In Europe, opal was long considered a symbol of purity, hope, and truth, and it was said to embody the virtues of all colored stones.
Tourmaline, though not traditionally linked to October until the 20th century, has a history of its own. Pink tourmaline, in particular, became an official October birthstone in 1912 when the National Association of Jewelers added it to the list. The inclusion of tourmaline was likely due to its vibrant colors and versatility in jewelry design.
Pink tourmaline’s history includes a notable chapter in Chinese imperial history. In the late 1800s, Chinese Empress Dowager Tzu-Hsi was so enamored with pink tourmaline that she purchased nearly the entire production of a California mine. She even used the gemstone for ceremonial purposes, as it was placed beneath her in a pillow at her funeral.
Both opal and tourmaline have rich cultural legacies, and their inclusion as October birthstones reflects their beauty, symbolism, and historical significance.
Geological Formation and Sources of October Birthstones
Opal
Opal is a hydrated amorphous form of silica, meaning it lacks the crystalline structure found in most gemstones. Instead, it consists of tiny silica spheres arranged in a lattice. These spheres scatter light in different directions, creating the mesmerizing "play-of-color" effect that makes opal so unique.
Opals form in near-surface volcanic rocks, where water percolates through the ground and deposits silica in cavities and cracks. Over time, the water evaporates, leaving behind the opal. Some opals even form in sedimentary rock, replacing the original material of fossils, shells, or wood.
The most famous opal sources are in Australia, which produces over 90% of the world’s precious opals. Other notable sources include Ethiopia, Brazil, and Mexico. Each location yields opals with distinct color patterns and characteristics.
Opal is relatively soft compared to other gemstones, with a hardness of 5–6.5 on the Mohs scale. Because of its amorphous structure and high water content, it is prone to cracking and requires careful handling.
Tourmaline
Tourmaline is a complex mineral group that includes over a dozen different species. The most common type in jewelry is elbaite, which can appear in a wide range of colors, including pink, green, blue, and even multicolored varieties known as "watermelon tourmaline."
Tourmaline forms in pegmatite deposits—coarse-grained igneous rocks that crystallize slowly, allowing large gem-quality crystals to develop. These deposits are often found in areas with geological activity, such as the Sierra Nevada mountains in California, where the Empress Dowager Tzu-Hsi once sourced her pink tourmaline.
Tourmaline is a relatively hard gemstone, with a hardness of 7–7.5 on the Mohs scale, making it more durable than opal. It is also stable under normal jewelry conditions, although it can be sensitive to sudden temperature changes.
Pink tourmaline, the October birthstone variety, is most commonly found in Brazil, Afghanistan, and Nigeria. Its vibrant pink to rose color is caused by trace amounts of manganese within the crystal structure.
Gemological Properties of October Birthstones
Opal
Opal is one of the few gemstones not composed of a single mineral. Instead, it is a hydrated amorphous silica, with no defined crystal structure. This gives it a unique appearance, but also makes it more fragile than most other gemstones.
Key properties of opal include:
- Hardness: 5–6.5 on the Mohs scale
- Chemical Formula: SiO₂·nH₂O
- Refractive Index: 1.34–1.36 (unmeasurable due to amorphous structure)
- Luster: Waxy to vitreous
- Specific Gravity: 1.90–2.20
- Color: A wide range of colors due to the play-of-color effect, often with a base color of white, gray, or black
- Transparency: Translucent to opaque
- Inclusions: Opals can contain bubbles, cracks, and other imperfections due to their formation process
Opal is often classified as either "precious" or "common" based on the presence of play-of-color. Precious opal exhibits the characteristic rainbow hues, while common opal lacks this effect and is more uniform in color.
Tourmaline
Tourmaline is a complex borosilicate mineral with a crystalline structure. Its chemical composition can vary significantly depending on the type, but the most common form in jewelry is elbaite, which includes a mix of aluminum, boron, and various trace elements.
Key properties of tourmaline include:
- Hardness: 7–7.5 on the Mohs scale
- Chemical Formula: Complex; varies by species (e.g., elbaite: Na(Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄O)
- Refractive Index: 1.62–1.64
- Luster: Vitreous
- Specific Gravity: 3.0–3.2
- Color: Wide range of colors including pink, green, blue, and multicolored (watermelon tourmaline)
- Transparency: Transparent to translucent
- Inclusions: Tourmaline often contains inclusions, which are considered part of its natural character
Pink tourmaline, the October birthstone, is especially popular for its gentle, feminine hues. It is also known for its durability, making it a suitable choice for everyday jewelry.
Symbolism and Metaphysical Beliefs
Opal
Opal has long been associated with mystery and transformation, making it a fitting birthstone for October. In ancient times, it was believed to possess the powers of all colored gemstones, combining their virtues and abilities. This made opal a symbol of hope, purity, and truth in European culture.
In the 19th century, opal gained notoriety in literature and folklore. Some stories portrayed it as a stone of good fortune, while others warned that it could bring misfortune to those who did not understand its nature. These beliefs contributed to a somewhat controversial reputation for the gemstone.
Metaphysically, opal is believed to enhance creativity, intuition, and emotional balance. It is also thought to promote love and happiness, making it a popular choice for romantic jewelry. In modern gemology, opal is often associated with the idea of change, reflecting its shifting colors and the seasonal transition of October.
Tourmaline
Tourmaline, particularly pink tourmaline, is associated with the heart chakra and is believed to promote love, compassion, and emotional healing. In ancient Egypt, tourmaline was thought to have traveled from the sun to Earth in a rainbow, carrying the colors of the sky with it. This myth reflects the gemstone’s vibrant color range and its connection to light.
Pink tourmaline is considered a heart-centered stone that encourages self-love, forgiveness, and emotional balance. It is often recommended for those seeking to heal from emotional wounds or build stronger relationships. It is also believed to bring a sense of calm and stability to the wearer.
Tourmaline is also known for its grounding properties. Some practitioners use black tourmaline to absorb negative energy and protect against electromagnetic radiation. While black tourmaline is not an October birthstone, it is often included in discussions of alternative or zodiac-related stones for October-born individuals.
Care and Cleaning of October Birthstones
Due to their unique properties, opal and tourmaline require specific care to maintain their beauty and longevity.
Caring for Opal
Opal is a relatively soft gemstone and is highly sensitive to heat and dryness. Because it contains water, it can lose its luster and become brittle if exposed to extreme temperatures or dry environments.
To care for opal, it is best to store it in a cool, moist environment, such as a sealed bag with a damp cloth. Avoid exposing opal to direct sunlight or heat sources like ovens, stoves, or radiators. Opal should also be kept away from harsh chemicals and abrasive materials.
When cleaning opal, use only a soft, damp cloth. Avoid using ultrasonic or steam cleaners, as these can damage the gemstone. If necessary, a mild soap solution and a soft brush can be used, but care should be taken to avoid scratching the surface.
Caring for Tourmaline
Tourmaline is more durable than opal, with a hardness of 7–7.5 on the Mohs scale. However, it can still be sensitive to heat and sudden temperature changes, especially when it contains inclusions or fractures.
To clean tourmaline, use a soft brush with mild soap and lukewarm water. A soft cloth can also be used to wipe the surface of the gemstone. Ultrasonic and steam cleaners are generally safe for tourmaline, but they should be used with caution if the gemstone contains inclusions or is set in a delicate setting.
Tourmaline should be stored separately from harder gemstones to prevent scratches. It is also a good idea to avoid exposing tourmaline to harsh chemicals or abrasive materials.
Both opal and tourmaline benefit from regular inspection by a professional jeweler to ensure that their settings remain secure and that any signs of wear or damage are addressed promptly.
Conclusion
October’s birthstones—opal and tourmaline—are two of the most captivating and versatile gemstones in the world of jewelry. Opal, with its iridescent play-of-color, and tourmaline, with its vibrant hues and diverse forms, each tell a story of transformation, beauty, and meaning. Their inclusion in October reflects the month’s themes of change and renewal, making them fitting symbols for those born during this time.
Whether you are drawn to the mysterious allure of opal or the gentle warmth of pink tourmaline, these gemstones offer a unique connection to history, culture, and personal expression. By understanding their properties, origins, and symbolism, we can appreciate the deeper significance of these October birthstones and the roles they play in our lives and jewelry.