What is black opal? Where is black opal found? How is black opal mined? How is black opal cut? How is black opal valued? FAQ: Why is black opal so valuable?
What is black opal?
Black opal is a type of Australian opal that is found in New South Wales.
Black Opal is also referred to as Lightning Ridge Opal or Lightning Ridge Black.
Australian Black Opal gets its name from the dark body colored common opal (black or grey) that hosts the bands of precious opal trapped inside the opal nuggets (nobbies).
Precious opal is opal with complex colors and patterns, often described as ‘play of color,’ that forms in seams, bands, veins or pockets within common opal or rock.
Common opal is opal that does not have ‘play of color,’ and is usually only one color.
Common opal and precious opal have the same chemical composition but variation in size and bonding patterns of the sphere particles. For this reason, they work with light differently. Learn more about what is opal here.
Black opal is precious opal hosted by black/grey common opal.
Black Opal Origin
Black opal is found in and around the township of Lightning Ridge in New South Wales.
Mining Black Opal
Black opal is found in pockets in clay beds.
In the old days’ miners worked in teams of two. One would sink the shaft with a pick and shovel and the other would bring the dirt (mullock) up in a bucket attached to a rope on a windless.
Nowadays the shaft digging is done with drills and the waste dirt (mullock) is bought to the surface with power winches or blowers.
The Lightning Ridge opal fields have been operating since the 1880s and over time have been worked extensively. As a result of this, Black opal like all varieties of Australian opal has become scarcer over time.
Cutting Black Opal
The first thing an opal cutter does when cutting an opal gemstone is to examine the raw material for color bands and face it down.
Rub or facing down, means that the opal cutter uses thin saws and fine diamond grinders to remove the clay and surplus common opal to expose the boundaries of the band of opal color captured inside the common opal and clay.
A cutter can make a good assessment on how to proceed by studying the edges of the band of color that has been blocked out.
Next, the cutter ‘faces down.’ This means they remove the common opal sitting on top of the band of precious opal to expose the color.
Sometimes the bands of precious opal are very thin in which case the cutter proceeds with great care.
Once the opal gemstone is ‘faced,’ the gemstone is shaped and polished.
To finish, the cutter polishes the back of the black opal gemstone.
Valuing Black Opal
Once a black opal gemstone has been cut and polished it is weighed and graded.
Grading is done on color, body tone, pattern and size (weight).
Experts grade the opals and set the prices relative to the rules of supply and demand.
FAQ: Why is black opal so valuable?
The production of black opal has slowed in recent times and as demand for this type of opal is high prices have gone up due to short supply.