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Opal gemstones - The jewel of Australia

Introduction

Opal can be called the jewel of Australia, since more than 95% of the opal that is found in the world comes from the great outback dry lands of Australia. This is a gemstone that exhibits a number of colors depending on the light. It is said to be fire and lightning; the easy patina of far-off seas, and all the shades of the rainbow.

The naming of opals


The name opal may be derived from several different languages, based on the meaning of the words, which aptly describe the gemstone. In Sanskrit, the name Upala means Valuable Stone, and this probably became the basis for which the Greek came up with the name Pallios, which loosely means Color Change. The Romans also had a word for this stone, and it was Opalus, which translates to Stone from Several Elements.

Scientists have described a phenomenon which is a characteristic of opals, and refers to the fact that they continually change colors; the term is Opalising. Opals have a character which brings about a sparkling change of colors within the same stone. The naming of the stone will depend on how the colors change, where they are located and the main color of the stone. The main color of the stone creates the following categories.

  • Dark or Black Opal
  • Light or White Opal
  • Crystal or Milk Opal
  • Opal Matrix
  • Boulder Opal
  • Mexican Opal
  • The Queensland Yowah Nuts, also referred to as the Picture Stones
  • Fire Opal also referred to as a Fine Opal Specimen since it is transparent, and does not have any display of colors.
  • Common Opal, which refers to opals which do not exhibit the characteristic display of changing colors.
The number of colors that an opal can show are unlimited, and each has a unique display, different from the next, even when they come from the same lode.

Legend and history of the opal.

There is a legend that dates back to the Ancient days, when Aborigines roamed the vast lands of Australia, and they believed a lot in dreams. It is said that the creator of heaven and earth, came down to bring messages of peace to all humankind, and did so by means of walking down a rainbow. It is said that the gems were lining the rainbow, and when his feet first touched the ground, the stone there became alive with these radiant colors; they say that this is why opals still keep showing the sparling changes of color.

Another story is told by the famous Roman author, Pliny. He says that an opal is a gemstone which combines the best of the various beautiful stones that are available in the world. He says that the stone has the deep blue of a fine Sapphire, the shining Purple of a royal Amethyst, the golden yellow of a Topaz and the fine sparkle of an Almandine. He said that all these characteristics came together and formed a fantastic display of colors.

Opals were very rare, but during the second half of the 19th Century, they became very popular. They were seen as the stones of the aristocrats, and this led to their commercialization. They were first brought to the gemstone cutters in Idar Oberstein, a popular gemstone center. When it came to Art Deco, the stones would be mixed with enamel, another very popular element then, to produce works of art and furniture. The creators of these works gave them different names depending on the characteristics of the opal stones which were used.

Why do opals change color?

There is quite a lot of fascination about the attractive play of colors exhibited by opals, but there is also a lot of curiosity about what causes this phenomenon. For a very long time, nobody came up with a satisfactory explanation as to why this was so. Then came the electron microscope, and in the 1960s, some scientists decided to put an end to all the conjecture around the stone. They found that an opal consists of several small spheres of silica gel, and these were the ones which were responsible for the color changes. They caused different refraction and interference to light rays, and this brought about the different unique color changes. These spheres are found in dense structures, and they dissect light as it passes through. This is why the colors of the rainbow are visible on the surface of the gemstone; the color display is never the same, and this adds to the mystique behind the stone.

History of Australian opal

It is true that over 95% of all the world’s opal is found in Australia, and they produce the list usually referred to as Fine Opals. Apart from Australia, there remaining 5% is mined from Northern Brazil, Mexico, Nevada, Idaho, and most recently from Mali and Ethiopia, in Africa.

The formation of opals in Australia started millions of years ago. There was a vast inland sea that covered parts of Australia, and a lot of stone sediment was deposited here. Later on, the waters filled up the seas, and they brought silica-bearing waters and filled the resultant cavities with them. The spaces of the sedimentary rocks, animals and plant reasons were filled with the water, and when the silica turned to stone, opal were formed. It can be said that the delicate nature of opals is because they are simply formed from silica and water. In other words, you can say that they are actually a gel which is formed from silica, but has varying water percentages.

In 1849, on Tarravilla, an Australian Cattle Station, the first blocks of opal were found. By 1890, at White Cliff, the first prospectors started mining opal, and the opals from this area are very popular to opal lovers. Other famous places where opals were found are Lightning Ridge, Andamooka, Coober Peddy; these happen be the most important opal places in the world. Lightning Ridge is the most important mining area, where the famous Black Opals are found. Andamooka is also famous for Light or Crystal Opal, and this is also where the largest opal in the world was found; it had a weight of 6,843 kilograms, which was aptly named the Andamooka Desert Flame. In the Aborigine language, Coober Peddy was the word which meant White Man in a Hole, and this was in reference to the way in which the prospectors used to mine the opal. Many of them dug holes in the rock, in which they would lay during the afternoon so that they could hide from the harsh sunlight, and also from the cold winds of the night. Opals were mined using shovels and picks, and the sol would be lifted using pails, and they would look for the opals in the loose rocks. Some of the shafts would reach depths of up to 40 meters and some would be as shallow as 5 meters.

Today, with the technological advancements of the day, it is possible to mine opals using tucks or conveyor belts. People still throng to the Australian Outback, in the hope that they would find opals which they would sell, and they would live comfortably for the rest of their lives.

The special cuts for the opal

The main characteristics of opals dictate that they should be cut in smooth shapes, which would best display the colors. Fine opal, which displays fantastic rainbow colors, are supposed to be cut in cabochons, which have a smooth dome shape on top. The fine Fire Opal, which is transparent and clear, is the only one which is cut in a faceted fashion. At first, all impurities are removed from the rough stone, by using a diamond cutting stone. After this, the stone is now shaped in the rough basic domed shape. The next step is finely cutting any rough edges from the basic shape, and then it is smoothened using a sandpaper. The final step is polishing the stone using a leather wheel.

There are times when opal is found as thin layers, also referred to as flat-lenses. It is rare that you get a bigger piece. You can then leave a thin layer of the hard mother rock of the opal, and get a pre-stage, for the creation of opal doublets. These are very common in mass-produced jewelry that has the opal stone. Such jewelry has a thin opal layer which is about 1 millimeter thick, and they are mounted to Obsidian, Onyx, Black Glass and Potch Opal. Apart from Opal doublets, you can also get triplets using this same method. Here the second later is covered by another cover of Lead Glass, Hard Glass, Plastic, or Rock Crystal.

Opals love the human skin and moist air

When opals lose the water stored in their structure, they become brittle and can form fissures, and the way the colors are displayed will become pale. Usually the stones should have at least 2 to 6 percent of water. The opals should never be stored too long, or exposed to a lot of heat, since this will destroy the characteristic that makes them valuable and beautiful. Therefore, this is one gemstone that should be worn as often as possible, so they can take in moisture from the human skin and the surrounding air.

When it comes to hardness, opals are relatively soft, with a value of 5.5 to 6 on the Mohs scale. The silica-gel structure is the reason why, and the fact that they have a lot of moisture in their structure. This is the reason why they should be set in a protective manner; this is the reason why they are sealed in protective resins; in the past, they were covered in oil.

Colors and the valuing of opals

The language that opal aficionados use to describe them and place a value on them can be very confusing for the uninitiated. They will use terms such as the Needle Fire, Harlequin, or Church Windows Opal. These terms were formed to describe the paly that the colors of an opal are displayed in. The terms can be very imaginative, and include others such as Flame Opal, Lightning and Peacock Opal, and those named above.

Although the body color is the main factor that determines the value of an opal, the transparency and the placement of the color display also play a role in this valuation. When you talk about body color, you are referring to the basic color, which can be described as Black, Dark, Light, and Colored. The transparency refers to the amount of light that goes through the stone; leading to transparent, translucent and opaque classifications. The opalizing of the stone can also affect the transparency.

When it comes to the combination of opalizing and the basic colors. The black opal is the best, since it displays the bright colors very clearly. The Crystal, or Light opal is the next on this list, and the colors are usually deep seated, unlike those of the dark opals which appear nearer the surface. The least expensive of opals are the milky opals, which have more diffuse colors. When it comes to occurrence, then you are talking about stones such as the Lightning Ridge Black Opals, which are some of the highest valued in the world, or the Mexican Fire Opals.

When it comes to the opalizing of the stone, then this is one of the most important considerations when it comes to pricing. The pattern, and play of the colors determine the price. If the dominant color is red, then the other colors will also appear reddish. The thickness of the opal layer is also a determinant of the price, the beauty of the pattern, the carat weight, finishing and patterning. All-in-all, the final appearance of the stone will determine the price that one has to pay for it. You could look for an expert to advise you if you want one that is truly exceptional.

Why opal gemstones are associated with emotions

For a long time, the Aborigine people believed that opals had the power to heal, especially the mind. They were used to heal depressions, and the person wearing it would find real love and peace in their lives. It is also said to be the stone of the Zodiac sign Cancer. The Boulder Opal was associated with Aries and The Black Opal was associated with Scorpio.

It is said that the changing colors reflect the changing moods in people, and that the stones would be used to reflect how the wearer is feeling on any given day. The colorful world of this gemstone is truly fascinating, and this is what people had opals for every single day, with their choice determining how they would feel for the rest of the day. Every human emotion is felt anew and differently, even under the same circumstances; something that is truly associated with an opal.



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