The white (or light) opal that was discovered in Australia 120 years ago is definitely the most recognized variety of opal and what most think of when the opal gem is mentioned. For centuries before the opal fields of South Australia this same variety of opal was produced in the opal fields of eastern Europe, the Hungarian opal fields. The Hungarian opal emitting a somewhat subdued play of color from a snowy white background was best known and most popular in Victorian England, mainly used for a girl’s coming of age gift symbolizing purity and innocence. The South Australian light opal was distinctly more colorful than its Hungarian predecessor capturing consumer attention and commanding greater value and position in the market as result. Today, 120 years after commercial mining in South Australia started the resource is nearly exhausted and production is a tiny fraction of peak periods. The new opal in the market comes from the Welo district in Ethiopia. The Ethiopian opal is spectacular in its best qualities with a play of color brilliance that exceeds the finest light opal from South Australia. That being said, there are mineralogical differences between these two varieties of light opal and as result, they have distinct differences in their appearance “personalities” and amazing differences in how they react to environmental exposure.
Australian opal is a bit fragile in terms of its resistance to breaking when hit.
Ethiopian opal is much more elastic and resists breaking much better than Australian Opal - it bounces like a rubber ball!
Australian opal is the hardest opal, with hardness similar to quartz - 6.5 mohs.
Ethiopian opal is much softer at about 4.5 mohs and will scratch easier.
Australian opal does not react well to intensely dry and warm environments. Long term exposure to desert-like conditions can cause a gem to craze or crack.
Ethiopian opal thrives in intensely dry conditions and performs best in desert-like environments.
Australian opal is somewhat sensitive to UV radiation which can cause a gem to have a less brilliant or weaker play of color.
Ethiopian opal does not show this trait.
The most amazing difference between these two forms of Opal:
Australian opal loves water and is impervious to most chemicals and the effects of soap/water exposure.
Ethiopian opal, when exposed to water, will lose its color play in its entirety, and when it drys the color play returns! Exposure to harsh chemicals, soap, and water, especially dirty greasy soapy water can permanently contaminate the gem causing it to lose its color display permanently. This aspect makes Ethiopian opal a little difficult for jewelry craftsmanship and difficult for the wearer to guard against this common exposure.
Acknowledging all this, despite its peculiarities the exceptional beauty and lower price of Welo opal will continue to draw consumer attention and market share.
The romantic ancient history of the Welo opal:
It is agreed that Welo Ethiopia opal is the ancient source of opal that Pliny the Elder first documented in vivid, romantic description 2000 years ago. Its spectacular and vivid play of color transfixed these ancient people leading the nobility and aristocrat class of this time to regard this opal as the most valuable of all gems. It is the opal that Mark Antony mercilessly pursued and was Cleopatra’s favorite gem.