Black Opal Gemstone Information
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About Black Opal - History and Introduction
Black opal is one of the many fascinating varieties of opal available today and it also happens to be one of the most popular varieties. In 2008, Australia officially recognized this and proclaimed black opal to be the official state gemstone for New South Wales. Common opal was already the official gemstone representing all of Australia, because, amazingly, almost all of the world's supply of black opal is mined from New South Wales and an astonishing 97% of all common opal is sourced from Australia.
Black opal is by far the most valuable and appreciated of all opal varieties, especially those from Australia's famous Lightning Ridge. Often, black opal stones will contain aspects of common opal which remain intact throughout production. Typically, common opal is strategically left on the backside of finished black opal stones. The common opal, referred to as 'potch', actually enhances the black opal body tone and accentuates the boisterous vibrancy of other colors that black opal can radiate. It is because of black opal's ability to display such vivid and intense colors that black opal is considered to be the most valuable type of opal available today.
Black opals can easily be distinguished from common opals by the color of their body tone. However, identifying natural untreated black opal from synthetic, lab created or treated opal can be nearly impossible without proper lab testing and equipment. Typically, if the black opal appears to be too colorful and too perfectly patterned, there is a good chance that it has been enhanced. Natural untreated black opal will typically always have flaws, which make the stone unique.
Almost all black opals are mined from Northern New South Wales and the majority of these are mined specifically from Lightning Ridge. Lighting Ridge has become known as the world's biggest supplier of black opal, and extracts incredible amounts of opal all year round. Other sources for black opal include Ethiopia, but Ethiopian black opal is usually enhanced through smoke treatment to darken the body tone color. No other origin or source can rival the quality and color of Australia's black opal.
Buying Black Opal and Determining Black Opal Gemstone Value
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Black Opal Color
Black opal body tones range from a dark gray to black, and the dark background acts as the base for the spectrum of colors it can display. Despite its descriptive name, black opal can, in fact, encompass various colors. Top quality specimens can reflect the full spectrum of colors through their unique play of color quality. Black opal contains subtle traces of iron oxide and carbon elements, which are not found in common opal. These combined elements are responsible for creating the unique traits belonging to black opal. The dark canvas of black opal results in the distinction and reflection of much brighter colors compared to other varieties of opal. Yellow, blue and green are the most common colors seen through play of color, whereas violet, fiery red and orange colors are the most valuable and sought after of opal colors.
Black Opal Clarity and Luster
Black opal clarity is typically translucent to opaque and almost all specimens will have eye visible inclusions such as patches or lines of potch (common opal). With black opal, it is the presence of crazing that can render a specimen worthless. Crazing is due to the drying of opal and it results in surface-reaching cracks or fissures. Black opal should have a wax-like luster, but at the same time, it should not appear to be too 'plasticky'.
Black Opal Cut and Shape
Typically, the shape and cut of a finished black opal will be dependent on the original opal rough. Black opals are most often cut into oval cabochons, but other shapes are also very popular, such as teardrops and trillion shapes. Most black opals are cut with low domes because they have rather thin color bars. If the opal color bar is too thin, it may be unfeasible to fashion any domed surface at all from the stone.
Black Opal Treatment
Australian black opal is typically untreated. Ethiopia is a major source for treated black opal. The treatment used on Ethiopian opal is an old smoking method which allows carbon to deeply penetrate the opal and enhance its color. There have been recently reported enhancements involving a combination of heat and sugar; stones are soaked in a sugar solution and then dipped in sulfuric acid. They are then slowly heated to produce a darker body tone.
Another treatment that has been discovered on some black opal is coating of the gem. This is not as common as heating, but nevertheless, consumers should be aware of this possible enhancement, along with the possibility of impregnation with polymer, resin or oil that is done to stabilize opal.
||SiO2_nH2O Hydrous silicon dioxide
||All colors, play of color
||5.5 - 6.5 on the Mohs scale
||1.37 - 1.52
||1.98 - 2.50
||Opaque, translucent to transparent
Black Opal Gemstone Varieties or other Similar Gemstones:
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There are many varieties of opal available and all of them can be classified as either precious opal or common opal. Ammonite, labradorite, mother-of-pearl and moonstone can sometimes be mistaken for opal.
Most Popular Similar or Related Gemstones and Trade Names:
Chocolate opal, boulder opal, fire opal, common opal, fire opal, white opal, opal in matrix and opal doublets are the most popular opal varieties.
Lesser Known Similar or Related Gemstones and Trade Names:
Layer opal, agate opal, angel skin opal, wood opal, honey opal, hyalite, hydrophane opal, porcelain opal, moss opal, jelly opal, crystal opal, harlequin opal, opal triplets, girasol, prase opal, pipe opal and wax opal are among the rarer opal varieties available today.
Black Opal Gemstone Mythology, Metaphysical and Healing Powers
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According to an old Australian Aboriginal legend, the Creator came down from the heavens on a rainbow and delivered a message of peace for all mankind. The stones which were near the place where his foot touched the ground suddenly became alive and began to sparkle - this was believed to be the birth of opal stone.
Opal stones are said to stimulate originality and creativity. Opals are porous stones and because they are porous, they are quite absorbent. With the ability to absorb, they can pick up thoughts and feelings of people and amplify their emotions. Black opals carry strong karma, representing justice and also providing protection for their wearers. Opal is also the official birthstone for October and those who wear opal can benefit from its many astrological powers.
Disclaimer: Metaphysical and Alternative Crystal Healing Powers and Properties are not to be taken as confirmed advice. Should you have any medical conditions, please see a licensed practitioner. This information is not to replace the advice of your doctor and GemSelect does not guarantee any claims or statements made. Gemselect cannot be held liable under any circumstances.
Black Opal Gemstone and Jewelry Design Ideas
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There are several advantages to buying loose gemstones, rather than preset jewelry. Once a stone has been mounted, it is almost impossible to know the actual quality because the setting often hides or obscures blemishes. Buying loose stones can also allow for greater variety and better value than buying pre-fabricated stock jewelry designs.
Despite being a softer, fragile stone, black opals are very often used in men's cabochon gemstone rings. Black opals have deep, dark colors which project masculinity and mystery. Black opals are ideal for any type of jewelry accessory such as pendants, earrings, brooches, men's cufflinks and tie-tacks. When wearing black opal as a ring, it is recommended to choose a protective style setting such as a bezel design.
Note: Buy colored gemstones by size and not by carat weight. Colored stones vary in size-to-weight ratio. Some stones are larger and others are smaller than diamonds by weight in comparison.
Black Opal Gemstones and Jewelry Care and Cleaning
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Opals have a high water content. In fact, their water content can compose up to 21% of their weight. It is because of this that they are very vulnerable to 'crazing' caused by dehydration. The drying of an opal will cause cracks and fissures that reach the surface. It is very important to always properly store and maintain opals, to prevent them from drying out. Opals are very sensitive to sudden temperature fluctuations. When storing opal gemstones, it is highly recommended that a moist cloth or cotton ball is placed inside a sealed plastic bag along with the opal to prevent dehydration.
Opals are fairly soft and because their hardness ranges from 5.5 - 6.5 on the Mohs scale, they can be easily scratched. Black opal stones can be cleaned by rinsing them under warm water and wiping them with a soft clean cloth. Never use bleach or chemicals and never use any ultrasonic cleaners to clean your opal gemstone. The vibrations alone can cause an opal stone to crack. Always remove opal jewelry before engaging in household chores or any vigorous physical sports or activities.
Damaged opals are extremely difficult to repair. Current repair methods are not official in the gem world, and so any method used today is only experimental. Typically, it is better to replace a damaged opal stone, rather than repair it. The most common methods used to repair damaged black opals include impregnating the stone with polymer or resin to fill in fractures or cracks.