Black opal is one of the most prized and valuable opal varieties known for its dazzling play-of-color and intense, dark body color. Here’s an explanation of black opal:
1. Formation: Black opal is a type of precious opal, which is composed of hydrated silica spheres. It forms in cavities and fissures in sedimentary rocks, primarily in regions with a history of volcanic activity, such as Lightning Ridge in New South Wales, Australia. The opal’s play-of-color is the result of microscopic silica spheres arranged in a grid-like pattern.
2. Color: Unlike common opals, which have a milky or translucent appearance, black opal displays a dark body color. The term “black” can be somewhat misleading, as it doesn’t necessarily refer to a completely black stone. Instead, the body color can range from dark gray to black, which serves as a backdrop for the vibrant play-of-color. The play-of-color in black opal can include a wide spectrum of colors, making it one of the most colorful gemstones in the world.
3. Play-of-Color: The play-of-color is the most distinctive feature of black opal. This phenomenon occurs when light diffracts and interacts with the silica spheres within the gem, creating a spectral display of brilliant colors, often in the form of flashes, patterns, or pinpricks of color. The colors can range from red and orange to blue, green, and violet.
4. Rarity and Value: Black opal is exceptionally rare and highly prized for its vivid play-of-color on a dark body. Its value is determined by the intensity and quality of its play-of-color, as well as the body color. The most valuable black opals exhibit a deep, vibrant play-of-color against a black or dark body.
5. Durability: Opals, including black opal, are relatively soft gemstones, with a rating of 5.5 to 6.5 on the Mohs scale. This makes them more susceptible to scratching and chipping compared to harder gemstones like diamonds. They should be handled and worn with care.
6. Origin: The primary source of high-quality black opal is Lightning Ridge, New South Wales, Australia. Lightning Ridge is renowned for producing some of the world’s finest black opals.
7. Jewelry: Black opal is often used in high-end jewelry, especially in the creation of rings, pendants, and earrings. The intense colors make it a captivating and sought-after gemstone for unique, one-of-a-kind pieces.
Black opal’s unique play-of-color against a dark background sets it apart as a truly captivating and collectible gemstone. Due to its rarity and stunning appearance, it is considered one of the most precious and valuable opal varieties in the world.