18.80cts Koroit Boulder Opal Polished Stone * AOH-3063

Item Information

Dimensions (mm) 25.9 x 15.3 x 4.7mm
Weight (carats) 18.8 carats
  • Cabochon
  • Polished

Down Under Opals

"Dreaming Opals"

The Koroit opal field is an opal mining area in Paroo Shire in South West Queensland, Australia. It is located about 80 km north northwest of Cunnamulla. It is not a town, nor should it be confused with the town of Koroit in rural western Victoria, Australia. It has neither electricity nor running water. Koroit is close to the town of Yowah which also produces a similar type of opal.

The Koroit opal field is known for the very distinctive type of boulder opal that is found in its mines. In Queensland boulder opal is found within a 300 km wide belt of sedimentary rocks in the Winton Formation. Here opal is found as a kernel in small concretions.

The Koroit Opal field was discovered in 1897 by Lawrence Rostron. The most recent mining events started in 1972 when the popularity and profitability of the stone increased. The mining is done by either open cut large scale mining or by underground shafts.


Stone :  Koroit Boulder Opal

Outback Queensland Australia

Cut and Polished. 

This beauty is ready to be set in jewellery. 

Natural and Untreated. (There is a lot of times that cutters use a epoxy to fill the natural holes in the stones which when you hold the stone in your hand it you get a plastic feeling. This has become a common practise)

Good pattern and colour

We use a 100mm Macro Lens to capture as much detail as possible, sometimes these details are not visible to the common eye.

Please note : Not all scales are made the same, so slight variation in measurements and weight are to be expected.

Also with finished stones we generally take thickness measurement in the middle of the stone.


Member of the " Queensland Boulder Opal Association "

Member of the " Lightning Ridge Miners Association "

100% Customer Satisfaction

Happy Bidding.

$300.00 USD

Add to Cart Make an Offer
Shipping $20.00
15 Days via Standard Shipping - Tracked
Add to Watch List Ask a Question * All prices in USD

Audit Information

The Opal Sheriff program allows our members to request an audit on any auction, which is completed by an independent Gemologist who assesses the accuracy of the item description and pictures.

Pricing & Details

Auction ID 1296885
Watchers 4 watching
Viewed 955 times
Starts 7th Nov 2022 2:27pm PST

Shipping & Insurance

Provider Shipping Transit
Express Shipping $40.00 14 days
FedEx $35.00 7 days
Standard Shipping - Tracked $20.00 15 days
Shipping Insurance all providers $20.00 (optional)

Downunderopals Details

You May Also Like