October is unique among the calendar months, boasting not one, but two recognized birthstones: opal and tourmaline. Both gemstones offer a captivating array of colors and possess a rich history steeped in lore and symbolism. This article will delve into the origins, properties, and significance of these fascinating gems, drawing upon available information to provide a comprehensive overview for enthusiasts and those seeking to learn more about October’s birthstones.
Opal: A Kaleidoscope of Color
Opal is a truly mesmerizing gemstone, renowned for its captivating “play of color” – the shifting flashes of iridescent hues that dance within the stone. This phenomenon is the defining characteristic of precious opals and sets them apart from common opals, which lack this spectral display. The formation of opal is a remarkably slow process, requiring approximately five million years for silica to solidify into the gem.
The genesis of opal begins with seasonal rains that permeate dry ground, particularly in regions like Australia’s outback. As water seeps into ancient underground rock, it carries dissolved silica downwards. During drier periods, evaporation leaves behind solid deposits of silica in cracks and layers within sedimentary rock. The interplay of silica spheres fusing together, creating tiny gaps that diffract light, is responsible for the vibrant play of color. The background color of an opal is determined by impurities within the silica, while the play of color itself arises from the diffraction of light.
Opal’s Global Origins and Historical Significance
Australia is currently the world’s primary source of opal, commercially producing the gem since the 1890s. However, opals are also found in Ethiopia, Mexico, and Brazil.
Throughout history, opal has been highly valued and imbued with diverse meanings. The Romans considered it the most precious and powerful of all gems. Bedouin tribes believed opals contained lightning and originated from the sky during thunderstorms. Ancient Greeks associated opals with prophecy and protection from disease. In Europe, the gem has long symbolized hope, purity, and truth. Beyond its birthstone status, opal is also traditionally gifted to celebrate the 14th wedding anniversary.
Evaluating Opal Quality and Appearance
The value of an individual opal is highly variable, akin to snowflakes or fingerprints – each gem is unique. Factors influencing value include the intensity and range of the play of color, clarity, cut, and carat weight. The cut of an opal is crucial for maximizing its color, pattern, and clarity, often resulting in non-standard shapes and domed surfaces to enhance the play-of-color.
Due to the difficulty in accurately capturing an opal’s true appearance in photographs, purchasing in person is often recommended. Sellers may enhance images, altering the perception of the stone’s play of color. Seeing the opal firsthand allows for a more accurate assessment of its beauty.
Opal Care and Maintenance
Opal’s hardness ranges from 5 to 6.5 on the Mohs scale, and its toughness is considered poor to fair. This makes it suitable for jewelry, but perhaps not ideal for pieces prone to heavy wear, such as bracelets or engagement rings. Opal is susceptible to fracturing from high heat or sudden temperature changes. Therefore, cleaning should be limited to warm, soapy water. Ultrasonic and steam cleaners are not recommended.
Tourmaline: A Spectrum of Hues
Tourmaline is another captivating gemstone offered to those born in October. Unlike opal’s play of color, tourmaline exhibits a wide range of solid colors, making it a versatile and desirable gem. Tourmaline ranks 7 to 7.5 on the Mohs scale, indicating good hardness and durability. Its toughness is considered fair.
Tourmaline’s Properties and Care
Tourmaline is generally stable to light and unaffected by exposure to chemicals. However, it is susceptible to damage from heat, which can alter its color, and from thermal shock caused by sudden temperature changes. Therefore, cleaning tourmaline jewelry is best achieved with warm, soapy water. Ultrasonic and steam cleaners are not recommended.
A Note on Paraiba Tourmaline
An exceptionally rare and valuable variety of tourmaline, Paraiba tourmaline, is noted for its vivid neon blue to green hues, caused by trace amounts of copper. A notable example, the Carolina Divine Paraiba, a 191.87 ct necklace, has been valued between $25 million and $125 million.
Conclusion
Opal and tourmaline, the birthstones of October, each offer unique beauty and a rich history. Opal’s mesmerizing play of color and ancient lore make it a truly enchanting gem, while tourmaline’s diverse range of colors and durability provide a versatile and enduring option. Both gemstones represent the vibrant spirit of autumn and offer a captivating choice for those seeking a meaningful and beautiful piece of jewelry.