• Location: Lightning Ridge, Australia
• Weight: 0.05g = 0.25ct
• Dimensions: 0.5 x 0.33 x 0.21 cm
• DETAILED DESCRIPTION

Australian Opal is renowned worldwide as the most important source of high-quality opals. The quality of Australian opals is primarily due to their intense and pure play of color. Thanks to specific formation conditions, they often display vivid and contrasting hues. This variety is reflected in the many types of opal found in Australia — from black and boulder opals to crystal, white, and matrix opals. Australian opals are notably more durable and stable than many opals from other locations. Their naturally lower water content increases resistance to temperature fluctuations and humidity changes, reducing the risk of cracking or drying out and making them ideal for everyday use in jewelry. Formation Australian opals typically form in sedimentary rocks such as sandstones and clays, found in large geological basins (e.g., the Great Artesian Basin, a vast underground water system covering much of Australia's interior). Silica-rich water gradually penetrates tiny cracks and pores in the rock. As the water evaporates or drains away, thin layers of silica remain in the cavities and can transform into opal. Microscopic spheres of silicon dioxide (silica) play a fundamental role: they arrange themselves in a regular three-dimensional crystal-like structure. This arrangement creates the characteristic "play of color," the iridescent effect visible when light strikes the opal. The color and intensity of this effect depend on the size and arrangement of the spheres. Deposits Lightning Ridge is a legendary opal field located in the Australian state of New South Wales, approximately 770 kilometers northwest of Sydney. This area is particularly famous for the so-called black opals, considered among the rarest and most valuable varieties in the world. History Mining activity in this area dates back to the late 19th century, but the real boom began in the early 20th century when explorers discovered opal-bearing layers with striking color effects. The name "Lightning Ridge" is linked to a legend that a shepherd and his flock died on a hill during a storm, struck by lightning. Reality or legend, this story gave the place a suggestive and memorable name. Types of Australian Opals Black Opal The rarest and most valuable type of opal, especially famous for the deposits around Lightning Ridge. It has a dark body tone (black, grey, or dark blue) that intensifies the play of color. Black opals often show the most intense color range, including red, green, blue, and purple. Boulder Opal Primarily mined in northeastern Queensland. It forms when opal fills thin veins present in iron-rich sandstones or other host rocks. This variety often retains part of the original rock, creating a contrasting backing. Boulder opals can have dark hues and display vibrant plays of color similar to black opals. Crystal Opal Characterized by a translucent or transparent body tone. Sometimes in its rough state, it may show little color, but once cut, it reveals prismatic flashes through a transparent or milky background. Crystal opals are found throughout Australia, with significant quantities coming from locations like Coober Pedy. White Opal (Light Opal) This variety has a white or milky-white body tone. It can display colors as vibrant as those of black opals, but they generally appear less intense because the light background reduces visual contrast. White opals are particularly common in Coober Pedy and are more accessible than black or boulder opals. Matrix Opal A special variety where opal is found within porous rocks such as sandstone or ironstone. After impregnation treatments, the colors can become much more intense due to the contrast created by the dark matrix. Andamooka is famous for these matrix opals, called Andamooka Matrix, which after treatment can resemble the rare black opals from other areas. Value The prices of black opals from Lightning Ridge can reach astronomical figures, depending on the size, saturation, variety of colors, pattern arrangement, and purity of the stone. The rarest specimens, especially those with a predominance of red or many bright hues, are considered among the most expensive gemstones in the world.