Our Opals

Types of Opals

Solid Opals

Solid Opal is Opal that has been mined and presented in its natural state after being cut and polished. It has not been chemically treated and has no other materials cemented to it.

Black Opal

Opal that is found with a natural black or a dark background color that gives greater intensity to the opal stone’s color. This is the most rare and most valuable type of opal. Black opal can be any color. Few people realise that 99.9% of the world’s supply of the radiant, dark lustrous gem is mined at only two tiny pinpoints on the globe, one of which is Mintabie.

White Opal

Not as rare as the black varieties but is nevertheless distinguished by lively color play. As the name suggests the stone ranges from transparent, translucent to nearly opaque with a creamy hue, displaying soft pastel shades of color.

Crystal Opal

This variety includes light or dark opal that is predominantly translucent when held up to the light. Color can be seen from deep within the opal.

Jelly Crystal Opal

A solid crystal opal that is extremely translucent to the point of being almost transparent.

Andamooka Black Matrix Opal

A more porous opal found in the mining fields of Andamooka. Matrix comprises precious opaline silica as an infilling of pore spaces in silty claystone. It generally shows fine pin fire colors in its natural state. The matrix opal is cut and polished, soaked in a sugar solution and then boiled in sulphuric acid depositing carbon in the available pore spaces which enhances its color. This type of matrix opal is exclusively found at Andamooka and is an attractive stone at comparatively good value.

Doublet

A doublet is a thin slice of opal that is backed by either a dark or black base to provide depth to the stone. This enables it to be set in jewellery and to emphasize the play of color. Such gems are considerably cheaper than solid opals yet provide the same play of color.

Triplet

Doublets are sometimes coated with a thin layer or dome of clear quartz making them more resistant to scratches. This produces a three-tiered gemstone known as a triplet that can often display brilliant colors. It is a cheaper method of presentation and can enhance the appearance of the opal as well as giving it a protective layer.

Rough Opal

Rough Opal is opal in its natural state, as it comes from the ground.

Determining the value of Opal

The value of opal compares favorably with many top quality precious stones and is the most valuable variety of the precious and ornamental silicas.

Attempts have been made to establish guidelines for determining opal prices but have been largely unsuccessful because of the gem’s infinite variation in color pattern. The value of individual stones varies so widely that pricing of parcels or stone is subjective, often dependent on the preference of the individual buyers (as quoted by the SA Department of Mines and Energy).

Below is a list of the main characteristics influencing the value of Opal:

Background color

Black opal (a gem with a dark background) is more valuable than transparent opal (crystal) which, in turn is more valuable than white or milky opal.

Dominant fire color

A stone with a strong color and a full spectrum range is generally more valuable than one with a predominant red-fire, which is more valuable than one with a predominantly green color which in turn is more valuable than a stone showing only blue color.

Color Pattern

Harlequin opal, where the color occurs in regular patches, is generally more valuable than pinfire opal where the color is in small specks.

Brilliance of color

The degree of brilliance is of paramount importance. The price of an opal is directly related to brightness. Patterns of colors, when combined with brilliance may increase the value many times.

Color

The red orange colors are the most highly prized. Care needs to be taken when applying this factor, as brilliance overrides all other factors. A blue/green brilliant stone will usually be more valuable than a dull red stone.

Shape

Oval, pear and other regularly shaped stones bring a higher price than irregular shapes (freeform) with the exception of Boulder opal, which is usually cut in freeform. A domed stone is usually more valuable than a flat stone.

Marks

Stones that have marks or cracks that are noticeable in the face of the stone will drastically reduced the value.

Weight

Solid stones are sold by carat weight. Dividing the cost of the stone by its carat weight will provide you with a guide to the stone’s overall value.