Opal Pictures
Precious, Black, Fire, Boulder, Jelly, Crystal, White Opal

Precious opal is a hydrous silicon dioxide material that flashes iridescent colors when it is viewed from different angles, when the stone is moved or when the light source is moved. This phenomenon is know as a "play of color" or an "opalescence". Most precious opals will flash a number of colors such as bright yellow, orange, green, blue, red or purple. Play of color is the characteristic of opal that makes it such a popular gem. The desirability of opal is based upon color Intensity, diversity, uniformity, pattern and ability to be seen from any angle.

Common opal is a hydrous silicon dioxide material that does not exhibit a "play of color". Common opal can be cut into stones, it can be attractive and it can accept a high polish. It simply lacks the play of color. Common opal is sometimes called "potch". Common opal usually has very little commercial value compared to precious opal; however, some exceptional pieces are sold for nice prices.

"Light opal" and "white opal" are terms used for opal material that has a white, yellow or cream body color. This is the most common body color for precious opal. The stone pictured at right is a white opal from Coober Pedy, South Australia. It weights 3.39 carat and is 18 x 7.5 millimeters in size.

"Black opal" is a term used for opal that has a dark body color, often black or dark gray. The term is also used for opal that has a dark blue or dark green body color. The dark body color often makes the fire of black opal more obvious. This contrast of fire color to body color makes black opals very desirable and sold for high prices. This specimen is a solid black opal with a strong blue face-up color play. It was mined at Lightning Ridge, Australia. It is 2.46 carats in weight and 9.5 x 12.5 millimeters in size.

"Fire Opal" is a term used for opal material that does not display a "play of colors". Instead, it has a bright color throughout the stone. Fire opal is often transparent to translucent. These stones can be cut en cabochon or faceted. The transparent stones are most often faceted and the translucent stones most often cut into cabs. Fire opal is a delicate stone, best suited for earrings, pendants and other jewelry that is unlikely to suffer impact or abrasion. It is not well suited as a ring stone. The specimen at right is a faceted fire opal cut from material mined in Oregon. It is 9 millimeters by 7 millimeters and weighs 1.2 carats.

"Crystal opal" is a term used for a transparent to translucent opal material that has a play of color within the stone. The stone shown here is an Ethiopian crystal opal with water-clear body colors and internal play of color. It is four millimeters across.

"Boulder opal" is a term used for a rough or a cut gemstone that displays opal within its surrounding rock matrix. Opal often forms within voids or fractures in its host rock and specimens of boulder opal reveal this aspect of opal's origin. The contrast of color can be striking when a bright flash of opal is seen within a the surrounding rock material. Many people enjoy the natural appearance of boulder opal and find these gemstones to be beautiful, interesting and educational. The specimen at right is a boulder opal from Australia cut into a bead. It is 10 millimeters by 6 millimeters in size, and weighs 1.9 carats..

"Harlequin opal" is a name given to an opal with patches of fire in the shape of rectangles or diamonds. The specimen at right is a harlequin opal from the Constellation Mine in Spencer, Idaho. It is 6 millimeters by 4 millimeters in size.

"Contra-Luz" is a name used for a color play that is visible when the light source is behind the stone. This effect only occurs in stones that are transparent or nearly transparent.

"Pinfire opal" is a name used for opal that has pinpoints of fire throughout the stone. The opal at right is a pinfire opal from the Constellation Mine in Spencer, Idaho. It is 6 millimeters by 4 millimeters in size.

Rarely, opal will have fire that yields an optical effect similar to a cat's eye. In these opals a thin line of fire will be visible from multiple directions and track back and forth across the stone similar to the cat's eye known in other stones. Shown here is a cat's eye opal from the Constellation Mine in Spencer, Idaho. It is four millimeters round.

An opal from the country of Peru in South America. Stones like this are often call "Peruvian blue opal". This stone was mined in the Andes mountians near San Patricio, Peru. It is 13 millimeters by 8 millimeters in size, ane weighs 2.3 carats.

Some wonderful opals are mined in the state of Idaho, USA. The stone at right was mined at the Constellation Mine near Spencer, Idaho. It is about four millimeters round..

Sometimes nationalities are used with other descriptive terms. The specimen at right is a "Nevada fire opal". Or, if we really wanted to be descriptive we could call it a "lemon yellow faceted Nevada fire opal. It is ten millimeters round and weighs 3.2 carats.

Who says common opal can't be pretty? Here is a really nice specimen of common opal with a beautiful purple color. This is opal is named after the city near where it was mined - Morado Opal from Mexico. It is 26 millimeters by 13 millimeters in size.

Australia is often said to be the "opal capital of the world" because so much opal is mined there. Here is a bead cut from Australian boulder opal. It is 15 millimeters by 10 millimeters in size.

One more to convince you that common opal can be really nice. This is a blue opal mined in the Owyhee canyon of Oregon. It is 20 millimeters by 11 millimeters in size, and weighs 8.1 carats.

Most cut opals are solid stones. The entire stone is cut from a single piece of rough (see top illustration). However, some opal rough has very thin but brilliant fire layers. Some artisans cut the stone down to the thin fire layer and glue it to a base of obsidian, potch or basalt - then cut a finished stone. These two part stones are called "opal doublets" (see center illustration). To protect the soft opal from abrasion and impact a crystal clear top of quartz, spinel or other transparent material is sometimes glued onto the opal. This produces a three part stone, called an "opal triplet" (see in the bottom illustration the clear cap, opal layer and base). The photo below shows two opal triplets, one face up and one upside down.

"Face-up fire" and "face-up-color" are terms used to describe a stone that presents a strong play of color when viewed from directly above. This is a highly desirable type of fire that makes an excellent presentation when the stone is set in jewelry. Stones that make their best presentation of color in the face-up position earn premium prices..

"Directional flash" is a term used for opals that do not display color in all directions. Instead, they display flashes of color when viewed from different directions or when the light source is moved. These stones also might have "dead angles" where they display little or no fire.

Some opals have been produced in a factory or in a laboratory. Synthetic stones are opal look-alikes made from materials other than hydrous silicon dioxide. Laboratory stones are produced in a lab from the same materials that compose natural opals. They often have an appearance that is very similar to natural opals. When sold as loose stones or in jewelry, synthetic and laboratory created stones should all be clearly marked for the buyer's information.