Opal Discovery #2


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.

A stunning black opal from Lightning Ridge showing red, orange, yellow, green and blue. Image: Giulians 2018

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.

In this boulder opal, there is one direction where the red play of colour covers most of the surface and another direction where hardly any colour can be seen at all. Image: Giulians 2018
This opal shows almost 100% colour coverage, from all angles of a 360 degree rotation. Image: Giulians 2018
This opal shows red flashes of play-of-colour, but not in all parts of the stone as it is rotated 360 degrees. Image: Giulans 2018

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.

Image: Giulians 2018
Clockwise from top left: Dark Body Tone, Medium dark body tone, Light body tone and crystal – all in black opal. Image: Giulians 2018

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.

A film photo of Ivan Vortouni in 1988, taken at Lightning Ridge, NSW after a day of looking around the opal mines, versus a digital image of Gary Coffey at work 2017.
In these two black opal examples the clarity and transparency of the opal on the right is a higher grade. Image: Giulians 2018

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.

This opal was recently made into a ring for a special client. While working on the ring, Joel took this  brilliant image of the red Chinese writing pattern. Photo Courtesy: @grumpyjoel

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

As this black opal is rolled from side to side, the flash of red travels across the stone. Image: Giulians 2018

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

As I rotate this black opal, the colours move but travel within their bands or ‘ribbons’, characteristic of this pattern type. Image: Giulians 2018

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

This black opal in this ring shows some straw -like pattern in the way its colours are small patches in a jumble of directions. Image: Giulians 2018

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

This Queensland boulder opal shows ‘pinfire, especially towards the top. Image: Giulians 2018

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.

Harlequin or checkerboard pattern in opal. Image: Giulians 2005

 

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@giulians.com.au or by filling out the below form.

Thanks for reading!

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By Alice | Posted on December 29, 2018

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