About opals

How are the opals formed and how do you know the difference between different opals.

How are they formed.

Opal was formed 20-100 million years ago, when there was a large inland sea in Australia. Without going into too much detail, opal is formed from a solution of silicon dioxide and water. Water has run down through the soil and absorbed silica from the sandstone. This silicon-rich solution has deposited in cracks and cavities caused by natural faults or the breakdown of fossils. As the water has disappeared, it leaves behind a silica deposit. This cycle is repeated over very long periods of time and eventually opal is formed. Some of the cavities have been plant material or animal bones. Therefore, we can sometimes find opalized bones, teeth and shells from prehistoric times. If you look at an opal through a microscope, there are small elevations in the opal. It is the height difference and the distance between the elevations that give the different play of colors when the light is refracted. You can compare it to making facets on diamonds, to give a play of color. The opal just has it from nature.

Solid opals

Solid opals are opals that have been ground and polished from raw opals directly from the earth. The raw opal is not treated in any way other than it is cut and polished. There are several different varieties of solid opals. These are Boulder opals - white opals also sometimes called milk opals - black opals - and Crystal opals. They are described in their respective sections.

Boulder opal

Boulder opal (natural type 2 opal) - found in a large area of ​​Queensland Australia from Longreach down to Quilpie Winton and Yowah. It is different from all other Australian opals as it has an ironstone as the host stone. The opal color or color bar itself is usually so thin that the opal grinder retains some of the ironstone as a background on the opal. Because of the thin color bar, many boulder opals are flat stones. Boulder opal gets its name from the way it is excavated. It comes up in large blocks of ironstone, called boulders. Other types of opal are Yowah nuts (the opal sits as a core in the center of a stone) or matrix opals (small lines of opal that run through the stone)

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White opal

White Opal (natural type 1 opal) - found mainly in South Australia (Coober Pedy and Mintabie are some of the most famous places) and in White Cliff in New South Wales. They are also sometimes called milk opal. It has a milky or white body tone, and is much more common than the black opal. It may have the same color bar on top as a black opal, but due to the lighter body tone, it is not as valuable as black opal. A solid white opal has 6-12% water content

Black opal

The black opal is the rarest and most precious of all opals. The vast majority of black opals are found in Lightning Ridge, Australia. It has a black background a normal opal with a layer of precious opal on top. The darker the black background, the stronger the colors in the opal appear. Opals from Lightning Ridge are divided according to how dark the back of the opal is. Light opal has a white or very light gray color. Dark opal has a gray to dark gray color. Black opal has a very dark gray to completely black. The darker the back, the more valuable the opal.

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Double opal.

Doublet opal - are thin layers of precious opal glued to a dark background. It can be a piece of black ordinary opal (potch), black plastic or ironstone. A rule of thumb is that a doublet opal is about 1/10 the price of a solid opal of the same size and quality. They are usually used to make pendants and earrings. Immersing a doublet in water is not recommended as water can get between the precious opal and the background where it is cemented together. By using doublet opals, we can produce beautiful and colorful jewelery at affordable prices, where you get more "flash for your buck".

Triplet opal

Triplet opal - is basically a doublet opal with clear dome glued on top of the precious opal, so it is three layers glued together: a dark base- a thin layer of precious opal and finally dome on top. The dome can be made of glass, plastic or quartz. It works almost like a magnifying glass. We do not make triplets or have triplet jewelry.

Crystal opal

A Crystal opal is an opal with color throughout the opal. This means that if you hold it up to the light, you can see through it.

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