Common opals may not show play-of-color, but they still form in gorgeous hues. Pastel varieties include soft pinks, greens, yellows, and blues. White opal is the most abundant color, while black opal and red opal are the rarest. The next stop on our journey through the difference between precious opal and common opal is all about the iridescent precious opal. A striking precious opal crystal from Lightning Ridge picture above exhibiting vivid play of color.
But how does it work? What causes play-of-color? Sanders and Peter J. Darragh, figured it out. All opals are composed of silica and water. At a microscopic level, the silica is in spherical shapes. With common opals, the spheres are disorganized and uneven. When opal forms, whether common or precious, other chemicals can get caught in the mix.
Precious opals can have a few different body tones, including white, black, yellow, and blue, to name a few. But did you know precious opal and common opal each have different varieties?
Common opals come in so many colors and varieties, listing every single one would be taxing to read. Agate opal is a variety with a banded color pattern on its surface. It can form around fossils or in rock veins. Despite the name, agate opal does not contain agate. Moss opal is found in the Ogallala Formation and contains inclusions of various iron minerals. The most common iron mineral present in moss opal is manganese oxide. Hyalite is special because of its clarity.
While most common opals have an opaque luster, hyalite is translucent. In most cases, translucent opals are precious opals. The feature that differentiates hyalite opal from other types of common opal is its unique bulbous clusters called "globules. The colorless variety forms in cavities of volcanic rock or in ore deposits coating secondary minerals. Peruvian opal refers to a category rather than a specific stone. Peru is known for producing gorgeous pastel opals.
The most popular of these soft shades are pink, blue, and green. Most Peruvian opals come from one of two provinces: Ica or Caraveli. Fluorescent opal is another fascinating category. Fluorescent opals can show glowing fluorescence under UV light. The stone usually glows in electric green color. Most of the gems with strong fluorescence come from Virgin Valley , Nevada. However, some opals can have a common opal version and a precious opal version.
Black opal has a common form and a precious form. That being said, plenty of opal varieties always show play-of-color and bring their own unique traits to the table. Remember how not all precious opals flash every color of the rainbow? Well, boulder opal is the exception. Boulder opal comes from Queensland, Australia.
Transparency - Opal of any body colour will be opaque, translucent or transparent. When it is transparent or very translucent, and the colour clarity is sharp, it is often referred to as crystal opal.
Black Opal is the most valued of Opals and comes mainly from Lightning Ridge. High quality stones are very rare. Easily distinguished by the blackness of the background "body tone" or body colour. It can be crystal or opaque. Because of its relative scarcity compared to light and even boulder opal, it tends to be more expensive, given equivalent colours, clarity and patterns.
Natural opals with a base tone ranging from colourless to medium grey are called light opal. Some people refer to these as "white" although this expression should only be used where the body colour is very milky. Light opal makes up the bulk of precious opal. White Opal may be transparent through to nearly opaque, although it usually has a "milky" appearance and has a light body tone or white body colour. Boulder is a variety of precious opal that has the host rock forming naturally as part of the gem.
Often just a thin vein of precious opal is present. It mainly occurs in specific locations over a wide area of Western Queensland.
Body Tone - The base tones of light, dark and black opal range from colourless, white, through the various shades of grey, to black.
Transparency - Opal of any body colour will be opaque, translucent or transparent. When it is transparent or very translucent, and the colour clarity is sharp, it is often referred to as crystal opal.
White Gilson Snythetic Opals. Share to:.
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