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The “7 Critical Facts You MUST Know Before Investing in an Opal!”. Written by Geoff McDonald (

Geoff McDonald and one of his sons Max

Hi, My name is Geoff McDonald and I’m the owner of the Brisbane Opal Museum and in charge of the opal jewellery in the shop. We're exclusively an opal shop (with adjoining museum). It’s all that we do, we enjoy it & we’re good at. And I’m not talking about your run-of-the-mill opal doublets/triplets, but quality 100% natural (solid) opals. What you will read from now on is based on 10 years experience in a modern opal business, what you get is not fluff, just facts...

“7 Critical Facts You MUST Know Before Investing in an Opal!”

The most you should ever spend on a doublet,

Why you should avoid a doublet ring,

The EIGHT characteristics that determine the true value of a solid opal,

Identify the different types of solid opals,

Insist on the stone being held by the metal,

The minimal opal thickness for a boulder opal ring,

The importance of an opal setting,

1) The most you should ever spend on a doublet,

A doublet is where a slice of opal is glued onto another stone, often the glue is black which makes the colour better. They have their place in our industry. However, I personally would not recommend spending any more than $500 on a doublet (loose stone) - and even less on a triplet. A triplet is basically a doublet (but the opal is thinner) with a glass dome glued on top (see image below).

A little mention here about Synthetic opal. Obviously it’s not natural and therefore it’s cheap (see pattern 1 & 2 below) - the good thing about it is that it is easy to identify. The pattern mostly comes in only two patterns (see below)...

"In our shop and on this website we only display solid 100% natural opals"

2) Why you should avoid a doublet ring,

Whatever you do, DON’T buy an opal doublet ring (gold or silver). Don’t do it. They’re too fragile. I have seen too many people show me a doublet ring which they purchased, which is now chipped at the edges - a triplet is better than a doublet for a ring, however they to have the issues as in time they can go cloudy due (because of water dissolving the glue).

3) The EIGHT characteristics that determine the true value of a solid opal,

1. Brightness - The most important factor regarding value is the brightness, brightness is the number one overriding-value-determining feature. Most opals look great in the sunlight but how does it look in low light. If you invest in a high quality opal it should still have good brightness in low light.

2. Type - Classic Solid Opal, Solid Boulder Opal, or Solid Matrix Opal.

3. Tone - Tone is not referring to any of the play of colour (sparkles/fire) but it is the secondary colour underneath (surrounding) the fire. The tone ranges between Completely transparent, to white-to-gray-to-black .

4. Shape - The more classic the shape the better (ovals are most preferred).

5. Thickness - The thicker the colour-bar the better

6. Colour - Think of a rainbow blue at the bottom red at the top. As you go through the colours from blue to red they get rarer - red is the most valuable.

7. Transparency - clear v's cloudy. The clearer the common opal is (opal without colour), which the play-of-colour (fire) is within, the more valuable.

8. Pattern - The more striking the pattern the better.

"The better these 8 features the more attractive it is and therefore the more people want it. In our shop and website we have a massive range"

4) Identify the different types of solid opals,

For more examples of solid opals please visit the Brisbane Opal Museum website - click here

Type 1 - Classic Solid Opal is where the whole stone is either precious opal or a mixture of common opal (potch) and precious opal. This type used to be the only opal called solid opal however, in the modern era often the word solid was used when what a customer really wanted was an opal that was 100% natural (type 1,2, or 3 NOT a doublet, triplet, treated or synthetic) therefore the industry has kept the word solid when an opal is 100% natural)

Type 2 - Is what we call boulder opal. It is where the opal is a layer of opal naturally attached to the host rock underneath (usually ironstone). So it’s basically two stones, ironstone and opal, (a doublet can look the same but it is glued not natural and this affects the look and value dramatically).

Type 3 . - Is what we call Matrix Opal. Matrix means to form inside of something else. So when we see a matrix opal we see on the surface of the stone ironstone and opal.

IMPORTANT: IN THE OPAL INDUSTRY THERE IS ALSO TREATED OPAL WHICH CAN BE CALLED A SOLID OPAL (sandstone matrix). Treated opal is where we take a tan coloured rock that has tiny little bits of colourful sparks that gets cooked in palm oil which turns the host stone black and makes the opal colour stand out - "Top quality black Matrix beads are awesome!" Here is an example of treated opal...

5) Insist on the stone being held by the metal,

If you invest in a solid opal ring make sure the stone is held in securely. Don’t just take the jewellers word for it. Take a close look at it. Make sure the stone is held in by metal not just glue.

6) The minimal opal thickness for a boulder opal ring,

If you buy a high quality opal ring (usually applies to boulder opal but can also apply to classic opal), make sure that the play-of-colour is not thin so that if needs to be re-polished in the years ahead it’s brilliance will remain (an opal ring might need repolishing due to tiny scratches due to minute scratches). "We ensure that all gold rings have enough opal to last a lifetime - and more!"

7) The importance of an opal setting,

7) On a scale of 1 to 10, how well is the opal protected by the setting? Regarding this scale there is no right or wrong answer however it is something that one should consider. It all comes down to the type of person you are (regarding body awareness) and the purpose of the opal piece - is it worn everyday or only on special occasions. If it was dropped on the ground (NOOoooo!) How well is it protected? "Experience has taught us how to best highlight the opal and protect it"

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