Australian Opals

Untreated Black Australian Opals: A True Natural Wonder
A person holds a curved, translucent blue and white fossilized Australian Opals in their hands.
Opal Formation: Where and How
A hand holding a large black Australian opal ring surrounded by diamonds, with the opal displaying vibrant multicoloured patterns.
How to Evaluate Australian Opals
Two halves of an opal-filled geode on a black background, showing iridescent colors inside a rough, stone exterior.
Opal Treatments & Synthetics & Assembled
Fine jewellery featuring an Australian opal pendant with diamonds, showcasing unique jewellery design and legacy gemstones
Australian Opals - Collector Series

FORMATION OF PRECIOUS OPALS - WHAT MAKES AUSTRALIAN OPAL A PRECIOUS GEMSTONE

Opal is the product of seasonal rains that drench dry ground in regions such as Australia’s semidesert “outback.” The showers soaked deep into the ancient underground rock, carrying dissolved silica (a compound of silicon and oxygen) downward.

During dry periods, much of the water evaporated, leaving solid deposits of silica in the cracks and between the layers of underground sedimentary rock. The silica deposits formed opal.

When this silica is deposited slowly under the right circumstances, it forms tiny, microscopic balls. When these balls compact and harden, they form opal. A considerable percentage of this opal is called common opal or potch.

Common opal is truly commonplace and is found across the globe. Unlike gem-quality opals, common opal does not exhibit the characteristic flashes of colored light.

Opal formation graphic
Precious vs Potch Opal

A remarkable transformation occurs when the minute silica spheres arrange themselves into a regular lattice structure. Light that penetrates the opal is reflected back from the stone through a phenomenon known as diffraction. The silica spheres disperse the light into a spectrum of rainbow hues.
When this phenomenon occurs, the opal is described as exhibiting a play of color or fire. Only stones that display this fire are classified as gem or precious opals.

HOW TO EVALUATE AUSTRALIAN OPALS

The most important factors are:

  • What Type (Natural & Synthetic & Reconstructed)
  • The Base Color (White, Crystal, Boulder, Black)
  • The Brightness (color spectrum, Intensity, Distribution)
  • The Weight (varies for every type of opal)

The assessment of precious opal should be conducted under controlled lighting conditions against a dark background. Rotating the opal relative to the background facilitates the determination of its type and aids in evaluating its play of color and cut.

A vibrant, multicolored Australian Black opal held between fingers, displaying a vivid play of rainbow colors.
Australian Black Opal

LESS VALUABLE TYPES OF OPAL

Educational graphic showing types of opal, including synthetic and treated versions, with text descriptions and visual examples.
An educational image comparing types of assembled opal: solid opal, doublet, and triplet, each with side views and descriptions of their compositions.
An infographic explaining matrix opal and its treatments including "solid matrix opal," "matrix opal treatments," and an australian source map, with photos and text descriptions.
Two books about opals displayed on a dark background with a starry pattern, titled "opals" by fred ward and "opal identification & value" by paul b. downing, ph.d.

OPAL TREATMENTS & SYNTHETICS & ASSEMBLED

Assembled Opal - Altered Opals have no intrinsic & Legacy value

Australian opal can be fragile. In solid opal cabochons, the gemstone material is typically sufficiently thick to endure everyday wear and jewellery repairs without fracturing. Manufacturers frequently reinforce with a rigid backing to enhance durability when using thinner material.
Assembled opals are crafted opals equipped with backings. These may include materials such as glass, which are not typically incorporated into gem-quality jewellery; nonetheless, due to their partial composition of precious opal, they retain gemstone value. They are priced at only a fraction of boulder opals, yet enable manufacturers to produce appealing finished gemstones from thin opal segments.
The two prevalent types of assembled opal are the opal doublet and triplet. The doublet comprises a thin layer of opal bonded to a backing, which is frequently made of ironstone, obsidian, dyed black chalcedony, black glass, natural common opal, or plastic. The triplet consists of a thin layer of opal sandwiched between a domed top of colorless quartz or clear glass and a backing of ironstone, obsidian, chalcedony, or black glass.

 

An elderly person's hands expertly crafting jewelry on a cluttered workbench, with tools and various small metal parts scattered around.

"sydney night life" 18.50 CT AUSTRALIAN BLACK crystal OPAL

Ring - Australian Black Crystal Opal

Opal ring in a box with brilliant play-of-color, displayed on a background of smooth stones, with a blurred qr code to the right.

Highly sought-after 15.46 CT Australian Black Opal - BLUE-RED Multicoloured

Australian Black Opal - One of a Kind - Exceptional Quality Ring

A hand holding a large, ornate Black Australian Opal with a gold setting, surrounded by diamonds.

Once in a life time "Africa" a 17.20 CT exceptional AUSTRALIAN BLACK OPAL

Australian Black Opal - One of a Kind 

Hand holding a very big luminous, iridescent Crystal Opal against the light

Very Big and Exquisitely transparent 86.00 CT AUSTRALIAN CRYSTAL OPAL

Australian Crystal Opal - Collectable Extreme Size