Black Opal Gemstone

Black Opal Gemstone

Black Opal Gemstone is of a hydrous silicon dioxide chemical formula. It occurs in an amorphous structure. It is formed when water carries silica through the earth, lodging it in crevices in the earth crust. These then became precious opals. It is revealed that it takes 5 to 6 million years to make a 1 cm opal to mature.

Unlike ordinary opals, black opals have carbon and iron oxide trace elements present, which cause the unusual darkness of the stone. Furthermore, the darkness of the opal is intensified by a black or grey backing called potch. The black brings out the stunning display of colors like the glowing aurora. The rainbow colors are actually the diffraction of white light from the tiny balls of silica left over after the water evaporated.

Opal has a hardness ranging from 5.5 to 6.5 on the Mohs scale with a refractive index ranging from 1.37 to 1.52. Black Opal gemstone are translucent to transparent.

Black Opal is one of the most popular variety of opals sold on today’s gemstone market. It is exceptionally rare in that it is known to form in only one place, Australia in the town called Lightning Ridge. Black Opal was recognized in 2008 as its official state gemstone of New South Wales, Australia. Australian opal has been cited as accounting for 95–97% of the world's supply of precious opal, with the state of South Australia accounting for 80% of the world's supply.

Black opals, such as those from Lightning Ridge, are generally considered the most valuable because the vivid and vibrant colors stand out with the black background. Its rarity also adds to its very high premium.

As with all expensive gemstones, there are always "counterfeits". There are synthetic, lab-created or treated Black Opal. The term "synthetic" implies that a stone has been created to be chemically and structurally indistinguishable from a genuine one. However, they can still be distinguished from genuine opals by their lack of inclusions and the absence of any surrounding non-opal matrix. Synthetic opals also do not fluoresce under ultraviolet light. They are also generally lower in density and are often highly porous.

In 2008, a new opal deposit was found in Ethiopia Wollo Province (Welo). This has become the dominant Ethiopian opal in the gem trade. The Black Opal here is usually enhanced through a process known as smoke treatment to make the opal darker.

In late 2008, NASA announced it had discovered opal deposits on Mars.

All specimen of Black Opal come with visible inclusions such as patches or lines of potch (common opal). Black Opal occur with a wax like luster but should not look like plastic.

The drying of the opal is called crazing and results in surface cracks or fissures. Crazing in Black Opal makes the opal worthless.

Black Opals usually are cut into oval cabochons, also into teardrops and trillion shapes.

Gemstones that can be confused with opal include ammonite, labradorite, mother-of-pearl and moonstone.

The most popular opal varieties include chocolate opal, boulder opal, fire opal, common opal, white opal, opal in matrix and opal doublets.

According to Australian Aboriginal creation myth, when the Creator came down from Heaven on a rainbow, the stones that the Creator touched with his feet became alive and began to dance and sparkle. This was how opals were created.

For the lucky Libras, the mesmerizing opals are the birthstone for the month of October.

Black Opal it is believed to give protection to the wearer. Many considered opal to be beneficial to the eye and wore it to cure eye diseases. Some even believed it could render the carrier invisible.

Opal stones are porous, that is to say, they have the ability to absorb. Thus, it is believed that opals can pick up thoughts and feelings of people and absorb the negative energy and amplify the positive emotions.

Black Opal gemstones are ideal for pendants, earrings, brooches, cufflinks and tie-tacks, and men cabochon gemstone rings. It is recommended that black opal ring be set in a protective setting such as a bezel design setting.

Opals occur with a high-water content. This water content makes up to 21% of the gemstone weight. Black Opal therefore are very vulnerable to dehydration, cracks and fissures known as crazing. To prevent your precious opal from drying out, store your black opal gemstone in a moist cloth or cotton ball inside a sealed plastic bag and stored away from harder gemstones.

You can cleanse your precious opal by rinsing them under water and using a soft cloth to wipe and clean them. Do not use bleach or other chemicals on your opal gemstones.