About opal : Solid opals

There is really something rare and extraordinary about the Opal . The Opal is set apart from other gemstones by it’s characteristic appearance, displaying sparkling colors which change and flash as you turn the stone in your hand. No two opals are exactly alike!  Solid opal is wholly naturally formed and is cut, shaped and polished from a single piece of material. When a solid opal is cut it will have a colored face and it’s naturally occurring different colored backing . This backing varies greatly and can include some color or all color but in most cases of genuine solid black opal, will be in a shade from black through to almost white, with no color at all. You can have very dark opals with very light backs, and vise versa but it is the darkness of the face of an opal that defines whether it is black, semi-black, or white opal.

Opal is composed of minute particles of silica in a closely packed spherical arrangement. Millions of years ago volcanic action caused the silica to flow into the cracks and crevices in the sedimentary strata of the earth’s crust. From time to time his liquid rich silica replaced the host item it engulfed. Over the ages of volcanic eruptions and the drying of Australia’s inland sea to a desert, sea and plant life became trapped over time in the layers of the earth’s crust and the liquid silica replaced them with the embryo of Australian opal. This is why opalized sea shells, ‘pipe’ opal (a tentacle of a squid) and even opalized dinosaur bones can be found some 600 miles from the nearest ocean.

It is believed that Australia’s island remoteness made it possible for complete calm and no seismic disturbance so that the silica spheres could perfectly align to create the most wonderful, beautiful colors that are found in Australian opals.

Black Opal

Black opal is characterized by a dark body tone. This dark tone causes all light to diffract so that every bit of color the opal holds within, will be seen by the viewer.

Black Opals are mined in the Lightning Ridge area of northern New South Wales, Australia. This magnificent variety in gem quality is the most prized and valuable type of opal. Ablaze with color, its dark appearance distinguishes it from Light Opal. The term ‘black opal’ does not mean that the stone is completely black,  (a very common mistake), it simply means the stone has a dark body tone in comparison to a white opal.

Light or White Opal

Found mainly in South Australia at Coober Pedy and Andamooka. Gem quality light or white opals show brilliant reds, greens and blues intermingled in a white or light background.
Found in both Lightning Ridge and South Australia. Jelly opal and crystal opal are solid opal, just a different type. Jelly opal, semi-crystal opal and crystal opal are all transparent or translucent. When they come from Lightning Ridge they have a darker tinge than the jelly and crystal opals from South Australia. In Lightning Ridge you mine nobby opal and seam opal. Nobby opal is the most prized and most expensive of all opals.

Jelly Opal/Semi-Crystal Opal/Crystal Opal

Found in both Lightning Ridge and South Australia. Jelly opal and crystal opal are solid opal, just a different type. Jelly opal, semi-crystal opal and crystal opal are all transparent or translucent. When they come from Lightning Ridge they have a darker tinge than the jelly and crystal opals from South Australia. In Lightning Ridge you mine nobby opal and seam opal. Nobby opal is the most prized and most expensive of all opals.

Jelly opal or crystal opal is basically speaking a solid nobby black opal that doesn’t have the natural black or gray backing on it which stops the light from passing through the opal and also makes it opaque unless viewed from an angle. What distinguishes a jelly opal from a crystal opal is the brightness, sharpness and intensity of color, crystal opal is much more highly prized than jelly opal.

Boulder Opal

Found in South Western and Central Queensland, this beautiful variety of opal can be very similar in appearance to Black Opal and forms naturally within ironstone “Boulder” which is cut to form part of the gemstone. The opal is naturally attached to the host rock in which it was formed and when cut this host ironstone rock is left on the back to enable all colors to be refracted to the viewer.

As in the case of South Australian and Lightning Ridge opal the silica may have replaced other organic material making it possible to find the most amazing opal fossils. Like the famous and magnificent “Yowah Nut” from central Queensland is one such occurrence, with its many veins of magnificent opal weaving it’s way through the ironstone host in ‘rivers’ and specks of glorious color. Many times when boulder opal is cut, some of the natural occurring ironstone is left in the face (top) of the opal, distinguishing it from the Lightning Ridge black opal.

Opal Doublets

Opal doublets are man-made from natural materials. A piece of solid precious transparent or translucent colored opal is adhered to a dark backing (usually black potch or ironstone) to imitate natures solid black or boulder opal. The dark base enables us to see the opal’s beautiful color by refracting all light and also adds strength and thickness. Doublets are most often produced with a very beautiful slice of opal that  is either too thin to be cut into a stone in it’s own right, or has no backing to allow the display of its color, the backing does not add any color to the opal.

It can be almost  impossible to tell a doublet from a solid stone, unless the sides of the stone can be examined (usually this requires magnification) to show the telltale line of black resin used for bonding between the opal and backing material. Doublets can be quite valuable and are also a very cost-effective way of possessing beautiful opal on a budget.  Doublets can also provide you with the opportunity to very nearly match a striking solid black opal to complete a set of matching jewelry ie earrings to match a solid opal pendant or ring. Due to the fact that the layers in a doublet are attached with resin it may become detached from it’s backing if immersed repeatedly in water. We  recommend you removed a doublet opal to bathe or swim. It is also recommended that inlay and doublet opals if set in rings, be treated with care as sharp knocks can easily chip these gems.

Opal Triplets

Triplets are also man-made and are made of three pieces of material – a  slice of  natural precious transparent or translucent colored opal, a cap of clear quartz and a black onyx base. A triplet is less expensive than a doublet because the slice of opal used is thinner than that utilized in a doublet. Because of the thinness of the opal, the quartz cap effectively protects the layer and allows us to see the beautiful colors below. Like doublets, due to the fact that the three pieces are attached with glue, water may affect the bonding material causing separation of the layers and if immersed in water repeatedly, the gemstone may take on a ‘foggy’ appearance.

Treated opal

Justopal.com do not sell treated opals however we are aware that treated opals do exist .Opals can be subjected to various types of treatment. These treatments may include color enhancement, heating, painting, dying, resins and waxes, oiling or an application of chemicals. At justopal.com we do not feel that treated opals can be considered to represent the true beauty of opals and feel that these types of treatment alter the natural beauty of opals giving them an artificial look. There is of course room for one very special type of treated opal, Andamooka matrix opal. This is a basically white, very porous type of opal that when boiled in sugar and sealed with acid can take on a ‘similar’ appearance to black opal but at a very fraction of the price. If Justopal.com ever decides to display these gems they will be VERY clearly identified in the description and heading. All treatments will be disclosed.

Care for your opals

With care, opals will retain their original appearance indefinitely. Opal care is not difficult and you should treat your precious opal with the same care and respect as you would with any fine jewelry. Solid opal does not need any special conditions, but it is advisable to avoid impacts and knocks.  If you live in an extremely arid climate it is a good idea to leave your solid opal in a glass of water overnight to rehydrate it (opal contains between 6% and 10% water). If your piece of opal jewelry is starting to look a bit dull, simply use water with a drop of mild detergent in it and brush it gently with a soft toothbrush, then rinse in clean water. Water will not harm solid opal.

Doublets and triplets can be wiped with a damp soft cloth but should not be soaked in water. The moisture may get between the layers making up the stone and spoil it’s appearance, or cause the bonding material holding the layers together to dissolve.

Opal has a hardness of about 5.5 to 6.5 measured on the Mohs’ scale of hardness. Compared to this diamonds are harder at about 10, garnets, the same at about 6.5 and gold is much softer at about 2.5 – 3. Therefore, opal like any other gemstone can be broken, chipped, scratched, or lose its shine with heavy wear and tear. Sand and soil are abrasive and ultimately will scratch the surface of the finely polished stone not to mention any gold or silver with it. An accidental hit or knock could crack the stone or damage the metal claws holding it into the setting .Treat all jewelry with respect and take it off before engaging in any of these activities.

After many years of wear, small scratches and scuff marks may cause an opal to lose its shiny polish and it may become dull looking. If your solid opal does become dull or scratched, you should take your opal to a reputable jeweler who knows about opal.  If the gemstone needs re-polishing this can generally be done for a very reasonable price. At the same time they can also check for claw damage and make sure that the setting is still sound. Professional re-polishing can bring new life to an opal which has become dull or scratched. If you cannot find a competent opal cutter to re-polish your opal, Justopal.com will offer this service to you.

If you need to store your opal away for a period of time, simply place it in a padded cloth bag for protection and store it away. Do not house it in a bank vault for long periods of time as these places are kept extremely dry and if left for a period of months or years your opal may loose all it’s moisture and crack. If you wish to leave your precious gem in a bank vault, seal it in a zip top bag in water and it will be fine for centuries