Have you ever wanted to know how to judge an opal’s quality?  In part two of Giulians’ opal discovery, lets take a look at the different qualities that make a great opal.

In a previous post, I hinted that there are many factors that go into determining a quality natural Australian opal.  However, it is important to remember that the best way to judge the beauty of an opal is by choosing the one that speaks to you!  It is easy to get distracted by the jargon and what is considered more valuable or rare, but personal taste and preference is still the most important thing to consider.  Each opal is millions of years in the making and a little piece of Australian history and they are all one-of-a-kind!

If you are interested to know what makes the difference between a good opal and an amazing opal – read on!

Qualities of Australian Opal

Colour

The colour you see is an important factor in an opals value, but it is not the only consideration. The colour red is the rarest to be found, and rarity does tend to increase value.  But amazing quality opal in any colour is rare – so even a super bright blue-green opal will be considered valuable – perhaps more so than an opal that shows only red and no other colours.  A gem exhibiting all five colours – blue, green, yellow, orange and red is very rare and desirable.

Colour coverage and colour direction

The percentage of an opal that is covered by colour will affect the value.  If an opal has 50% of the stone showing bright play-of-colour, and the other 50% showing darkness or minimal colour, this opal will be valued lower than an opal with 100% of its surface covered by bright colour.    The direction the colours are seen will also affect the value of a gem, as some opals will show a bright flash in one direction, and then darkness in another.  This opal would be considered perfect for a pendant, as they are generally only worn in one direction, and we would set it in the direction of it’s brightest colour.

Body Tone

One surprising factor of an opal’s appearance is the body tone.  Body tone refers to the general colour of the opal, ignoring the play-of-colour.  This is by looking at the common opal or ‘potch’, which is the greyish – black material that is seen on the back of a black opal, and the greyish white that is behind some white opals.  You may hear some references to a body tone colour chart, like in the image below, but at Giulians we prefer the terms Black (N1-N4), Semi-Black (N5-N6), Light (N7-N8), White (N9) and crystal.  The darker the body tone, the more contrast and intensity of the play-of-colour will be seen, increasing the value.

Transparency, Clarity, and Brightness

One of Gary’s favourite analogies for judging clarity in opal is by comparing it to analogue versus digital photography.  Holiday snaps that were taken hastily on film and developed, would often have a grainy or slightly cloudy appearance, in comparison to the crisp clarity of the digital photography of today.  Some opals will have a certain clarity of colour, and crispness that just makes the colours pop.

Pattern 

The pattern in opals can affect the value, as some patterns are more rare than others. There are many names given to the patterns seen in opal, and I have listed a few of the more famous ones below.

Chinese writing – This pattern has very linear and crisscrossing colour patches that resemble the look of Chinese characters.

Rolling flash – A bright flash that travels across the opal while it is being moved.

Ribbon pattern – This pattern is reminiscent of the texture of satin ribbon, where bands of colour run parallel to each other.

Straw – Straw pattern is characterised by small but linear patches of colour in a mix of intersecting directions.

Pinfire – As the name may suggest, pinfire pattern is made up of tiny pinpoint colour patches, resulting in an overall glittery effect.

Harlequin – this is the rarest pattern in opal.  Giulians have had some stunning examples of this pattern in the past, like the black opal in the image below.

I hope you have enjoyed reading about some of the qualities that make an Australian opal so unique.  If you would like to know more about our opals, or any of our opal pieces please get in touch at giulians@old.giulians.com.au or by filling out the below form.

Thanks for reading!