Opal, celebrated as one of the birthstones for October alongside tourmaline, is a gemstone renowned for its captivating play-of-color. This unique optical phenomenon, a shifting kaleidoscope of hues, has inspired folklore and admiration for millennia. While historically recognized as the primary October birthstone, its status has evolved alongside changing traditions within the jewelry industry. This article will delve into the history, geological origins, gemological properties, and cultural significance of opal, drawing solely from available sources.
History and Lore
The story of opal’s name is somewhat enigmatic. Most accounts trace its origin to the Latin word opalus, first recorded around 250 BC, but the ultimate source remains debated. Some scholars suggest a connection to the Ancient Greek opallios, meaning “to see a change in color,” aptly describing the gem’s defining characteristic. Others propose the Sanskrit word upala, meaning “precious stone,” as a more likely root.
Ancient civilizations attributed various powers and meanings to opal. Ancient Greeks believed the stone bestowed the gift of prophecy and offered protection from disease. Romans considered opal a symbol of hope and love, and the term opalus itself signified “precious stone.” For centuries, opal was thought to embody the virtues and powers of all colored stones combined. Bedouins held the belief that opal contained lightning and fell to earth during thunderstorms.
However, opal’s reputation hasn’t always been positive. A superstition emerged, likely in the 19th century, suggesting it was bad luck to wear opal if it wasn’t one’s birthstone. This belief may have been popularized by Sir Walter Scott’s 1831 novel Anne of Geierstein, where an opal’s changing colors mirrored the protagonist’s moods, ultimately fading with her death. This narrative contributed to a period of diminished popularity for the gem. Despite this, opal remains the stone associated with the 14th wedding anniversary.
Geological Formation and Sources
Opal is unique in that it is not a crystalline mineral but rather a mineraloid – a naturally occurring amorphous substance. It forms from the gradual natural heating of silica gel found in cracks and crevices within rocks. This silica gel, dissolved in rainwater, percolates into the earth, particularly in regions with dry ground. As the water evaporates, deposits of silica are left behind, slowly building up to form opal.
Historically, India was the primary source of opals brought to the Western world, giving rise to the Sanskrit name upala. However, the most abundant sources today are found in Australia, particularly in its outback regions. Significant opal deposits are also located in Ethiopia, Mexico, and Brazil, with smaller occurrences in the United States, Central Europe, Honduras, Indonesia, Madagascar, Peru, and Turkey. The geographical origin of an opal can influence its distinctive character and the hues displayed in its play-of-color.
Gemological Properties
Opals are broadly classified into two categories: precious and common. The defining characteristic separating these categories is the presence of “play-of-color” – the iridescent display of rainbow hues. Precious opal exhibits this phenomenon, while common opal does not. This play-of-color is caused by the diffraction of light as it passes through microscopic spheres of silica within the stone.
On the Mohs hardness scale, opal ranks between 5.5 and 6.5, making it relatively softer than many other gemstones. This lower hardness requires careful handling to avoid scratches and damage. Opal is composed of hydrated amorphous silica (SiO2·nH2O), meaning it contains water within its structure. This water content contributes to its instability; opals can deteriorate over time, losing their color and becoming chalky as the water evaporates. This transformation from a vibrant, glassy stone to a colorless mass is a known phenomenon.
Symbolism and Metaphysical Beliefs
Throughout history, opal has been associated with a range of symbolic meanings. It has been linked to confidence, hope, and truth. Some modern interpretations suggest opal encourages emotional expression and creativity. The stone’s shifting colors have been seen as a reflection of the wearer’s moods, as depicted in the fictional account within Anne of Geierstein.
While not explicitly detailed in the provided sources, it is worth noting that the variety of colors within opal allows for a broad range of interpretations and associations, making it a versatile stone for those seeking symbolic meaning in their jewelry.
Care and Cleaning
Due to its relatively low hardness and water content, opal requires specific care to maintain its beauty. It is susceptible to scratching and should be protected from impacts. Avoid harsh chemicals, ultrasonic cleaners, and steam cleaners, as these can damage the stone. Cleaning opal jewelry can be done gently with a soft cloth and lukewarm soapy water. It is important to avoid prolonged exposure to heat or direct sunlight, as this can cause the opal to dry out and crack.
The Rise of Tourmaline as an Alternative
In 1912, the National Association of Jewelers introduced pink tourmaline as an alternative birthstone for October, alongside opal. This decision was later approved by the American Gem Society and the National Retail Jewelers Council in 1952. Pink tourmaline is often associated with friendship, compassion, and balance. The Egyptians believed tourmaline’s diverse colors originated from its journey down a rainbow from the sun to earth. This addition provided jewelers and consumers with a wider range of options for October birthstone jewelry.
Conclusion
Opal, with its mesmerizing play-of-color and rich history, remains a captivating gemstone. From ancient beliefs in its prophetic powers to its modern status as a cherished birthstone, opal continues to inspire and enchant. While its reputation has experienced fluctuations over time, its unique beauty and geological origins ensure its enduring appeal. The addition of pink tourmaline as an alternative October birthstone offers a broader spectrum of choices for those celebrating a birthday in the tenth month.