Australian Opal (Mix)

Buying this parcel

Where it came from, what its weight band is for, and what to check before any money changes hands.

The deposit

This parcel is Australian without being tied to one field, which for opal is a meaningful statement rather than a vague one, because the three producing regions yield visibly different material. Lightning Ridge gives dark body tones, Coober Pedy gives white and light opal with a milky ground, and the Queensland fields give boulder opal still attached to its host ironstone. A mixed Australian parcel therefore holds real variety of ground and pattern, which is exactly what you want if you are selecting for a look rather than filling a specification.

This parcel

Five to twenty five carats is a wide band and opal is where width is most useful, because opal is not priced on weight in anything like the way a faceted stone is. A five carat stone with broad flashes of red across the whole face can be worth many times a twenty five carat stone whose colour dies at one angle. That decoupling means a parcel like this has to be selected by eye, one stone at a time, and cannot sensibly be bought to a weight. Come with a pattern and a colour in mind rather than a carat number.

Treatment

Unheated and untreated, and solid rather than assembled, throughout the parcel. Doublets and triplets circulate heavily in mixed opal goods precisely because a parcel is where they are easiest to hide, so this is the disclosure that matters most in this lot. No smoke treatment and no sugar treatment either, both of which darken body tone artificially and both of which are more common in parcels than in single stones.

The report

No report is held for this 5 to 25 cts opal parcel yet, and we would rather say that than name a laboratory that has not seen it. We will submit whatever you select to IGI or IIGJ before purchase on request.

Before you pay

• Check every stone you select from the side for a join line. In a parcel this is the single most valuable ten seconds you will spend.
• Rotate each candidate through a full turn under one light and watch for the colour going flat in any direction.
• Look for red in the play. Red is the scarcest colour in opal and the one that moves the price most.

Read next

Heera, the diamond covers the material itself and what gets sold in its place. How to buy a coloured stone covers pricing, treatment and reports.

Written by Kamal Kishore Agarwal, founder and gemmologist, Gem-A qualified, buying in Johari Bazaar since 2008.