Taken from a Quora article we answered a few years back.

See the video below from our last trip that reflects many of our endeavours that end with very little to show for the time and expense...

Answered Oct 9, 2017

The reason high quality opal is so expensive is because it is genuinely rare, and usually breathtakingly beautiful.

I have mined for over 30 years as an artisan miner on the Coober Pedy Opal fields in the South Australia outback, and I can say that I found over a million in opal, but over the span of my career it works out to about, $300 per week…

This is not for lack of trying or professionalism, it is just that quality opal is extremely rare. For example, every time we found say, 100 ounces of material, it was extremely consistent that 90% would be almost worthless, 7% would be potch and colour worth very little, 2% would be medium grade worth maybe a few hundred dollars an ounce and 1% would be one thousand per ounce or more (high quality) This was almost always from good fields where the opal was known to be clean and stable.

Even when there has been an abundant supply from a new field and the prices are depressed, it never lasts long, simply because the geological conditions required to create large quantities of quality opal are as rare as the opal itself, of course, they are inextricably linked.

Not to mention the sheer risk, expense, hardships, and continuous challenges faced by the miner while tunneling 60 feet underground, it costs the average full time professional small syndicate a minimum of 100 thousand a year to tunnel a claim, with zero guarantee of a return..

to summarise, if quality opal was abundant and cheap to obtain and filled the jewellery market with beautiful top quality material, every one could get a showstopper for ten bucks a piece.. but that’s probably not happening any time soon..