Opal Buying Guide

Before Buying Opal or Opal Jewellery, there is some important & valuable infomartion that can be of help. The following Opal Buying Guide will give you some insights into dealing with, and deciding which Opal is best for you. If you are an Opal lover, Opal addorer or simply want to learn as much as possible about Opals then the following Guide is for you:


The first step is to get a quick overview of the different Types Of Opals that are available to you. Opals come from many different parts of Australia and have distinct differences in appearence. The colors & patterns can change drastically.

Natural Opal

  • Boulder Opal or Matrix Opal: Boulder Opals also known as matrix opals occur as deposits in ironstone creating a very hard backing. When the Opal is cut the Ironstone is left at the back creating a strong and unique backing which adds to the look of the Opal. While normally cheaper then their expensive cousins the Black Opal, Boulder Opals can still rival them in terms of brilliant colours.
  • Black Opals: Black Opals the so called ‘King of Opals’ have a dark body tone and more often then not an impresive array of colours. The most expensive Opals overall due to their rarity & look.
  • White Opals: White Opals are quite common and are called so due to their white body tone. While they tend not to reflect colour as well and are often less valuable than Black Opals a high quality White Opal is still stunning.
  • Crystal Opals: Crystal Opals have a transparent to semi transparentlook. This effect can occur in any type of stone and with a good colour can increase the Opals worth.
Modified & Man Made Opals
  • Opal Doublets: Opal Doublets consist of a solid piece of Opal that has been glued to a back backing. If you look closely you will be able to see a slight line where the join is. Opal Doublets are worth a lot less then a full Opal.
  • Opal Triplets: Opal Triplets are an Opal Doublet but with a clear piece of hard plastic or glass attached over the top of the Opal. The Opal with have a ‘glassy’ look if viewed from above. An Opal Triplet is worth considerably less then a full Opal.
  • Synthetic Opals: Synthetic opals are made of materials which have the same composition and physical structure but are man-made. Synthetic Opals usually appear glassier than natural opals and have a precise and organised colour scheme, typically in a snakeskin pattern.

Like most gemstones, opals can be set as rings, pendents, earrings & bracelets.


Selecting an opal can be tough but there are some factors that can be taken into consideration to help you make sure you are getting what you pay for & getting something that you what. The following points are not the be all and end all but are more of a guide to help you make a decision.

Unlike Diamonds, Rubies, Sapphires and other gemstones Opals don’t currently have an official valuation process. While the Opal Association is working on a body tone guide there are some clear contributing factors that help determine the value of an Opal. The range of play of colours, patterns, opal class, body tone, brilliance, thickness, colour bar and faults are the important factors on how Opals are valued.

Play of Colour (Spectral Colour Range)

Play of colour refers to the colours of the Opal reflecting from lots of different angles. The range and coverage of the play of colour is a big factor in determining the value of the Opal. The very best Opals will have a play of colour across the whole surface from multiple angles. However most Opals will not have a play of colour across the whole gemstone but have a stunning or unusual pattern including colour ribbons, harlequin, a flash of colour, rainbows and other variations. Remember every Opal is Unique there will be beautiful flashes of Red, Green & Blue depending on the Opal!

So the more play of colour across multiple angles means the more expensive the Opal. Even just a few angles that have an explosive play of colour will increase an Opals value considerably. All angles and play of colour is valuable at some level, for example if an Opal displays amazing colours from the side or slightly above the Opal then it would be particular suited to an Opal Pendant.

Definitely have a look at the different angles of an Opal to see how ‘explosive’ the colours are and if an opal doesn’t have any play of colour, you can be pretty sure it isn’t precious opal!

The Opals Colours

Red colours in the Opal are the rarest and therefore the most valuable followed by orange, yellow, green, and then blue being the most common. However while certain colours are worth more than others the most important thing is to find colours that you like.

The Pattern of the Opal

Terms such as fire, harlequin and rainbow describe the unique interplay of colour in an Opal. The most sort after pattern tends to be the Harlequin. The Harlequin pattern refers to angular & broad close set patches of colour. It is also extremely rare to get a true harlequin pattern so be careful what the Opal seller is claiming.

This refers to the amount of light and the hue that an Opal reflects. More valuable opals show brilliant flashes of colour while lesser-quality opals have dull or subdued colours. There are two big considerations you need to take into consideration when you are determining an Opals brightness.

  1. There are two common ranking systems that can be used to rank an Opals brightness. The first is a simple 1 to 5 scale. The rankings are as follows: 1 Faint, 2 Dull, 3 Bright, 4 Very Bright, 5 Brilliant. There is also another system that the Opal Association is working on that ranks the opposite way and from 1 to 7. The following is for Black Opals but shows you how it works:

  1. The other big consideration is how you are viewing the Opal. The colours & pattern you are seeing depends entirely on the angle and somewhat on the light. If you are looking at Opal pictures on the internet be sure to adjust your monitors contrast as it can drastically alter what the Opal looks like. If you are viewing in person then sunlight and lighting from warm bulbs will tend to bring out more warm tone colours, reds, oranges, yellows, purples and magenta while viewing your Opal in the shade or in less direct light will tend to bring out the blues and greens.

Body tone (Colour Background)

Body tone is used to describe the comparative lightness or darkness of an Opals background. You can tell an Opals body tone by looking at the Opal from the front only. The scale of body tone ranges from N1 to N9 with N1 being the darkest and N9 the lightest. To be classified as a Black Opal the stone must have a rating of N1 – N4, White Opals have a body tone of N7-N9 while light grey, grey, and semi-black opals fall in the middle.

opal body tone scale

Faults & Flaws of the Opal

Opals with cracks, inclusions, or other faults become less valuable. Some of these are natural while some are man made and if you can accept having a fault in the Opal you can find some great bargains sometimes! Here are few types of Opal faults:

  1. Potch lines are lines that occur across the Opals face. A lot of Opals will have Potch lines that don’t actually stand out, these are fine and cause no issues with value. However a common type of Potch lines are grey lines across a Black Opals face which would decrease that Opals value.
  2. Sand or Clay marks are small pieces of rock or clay that was present when the Opal was being formed. Matrix Opal is a classic example of this and there are some amazing examples that you can find. While the value of Opal with sand marks might be lower there are some amazing patterns created.
  3. Cracks and Scratches can also cause an Opals value to decrease. If the scratches are only on the surface of the Opal then once the Opal has been professionally polished to remove them the value will increase. Cracks that go through the thickness of the opal’s surface will reduce its value. 


Choosing an Opal That You Like

Choosing an Opal That You Like is probably the most important factor in choosing an Opal. Even taking all the above valuation information into consideration means nothing if you don’t like the look and feel of the Opal on a personal level. While one of the most appealing combinations is Red Opal on a Black Opal it doesn't matter if you prefer Blue Opal follow than your heart! Thats the great thing about the uniqueness of Opal each stone has its own inner beauty and personality.

What is the Purpose of the Opal?

What is the Purpose of the Opal? Before buying an opal its worth thinking what you are buying the Opal for. Are you making it into an Opal Ring, Opal Pendant or pair of Opal Earrings? You might want to buy a high quality piece fro a wedding ring or a piece of Jewellery that is for a special occasion.

Certificates of Authenticity or a Money Back Guarantee

If possible get a Certificates of Authenticity or a Money Back Guarantee when buying an Opal Online? It makes the seller accountable for the Opal they are selling and allows you to get comfortable with the Opal you have bought.

Will I Get Exactly What I See in the Pictures?

One of the most common questions we get is will the Opal look like its pictures. With the massive trend to buying Opals online it is a very valid question. The brightness, texture, brilliance of an Opal depends a lot on the camera that was used to capture the pictures. Here at Macs Opals we strive to portray the Opal as accurately as possible. A lot of of Opals will also have Videos to give you even more detail.

Is it Safe to Give Out My Credit Card Details Online?

We completely understand the need for a high level of trust when buying online. Will I get the right stone? Will it be what I wanted? We at Macs Opals want to help make your shopping experience as safe as possible – so we offer a 30 Day No Questions Asked Money Back Guarantee and the highest credit card security when purchasing online.


If you still aren’t sure about what Opal to Buy then we recommend learning as much as you can about Opals. We have plenty of resources on Macs Opals that can help you. You can read our: Blog or Opal Guide Articles to learn more.

There are also some good sources online:

We hope that this Opal Buying Guide has helped you with your decision of purchasing an Opal or even Opal Jewellery. If you have any questions or if we are missing something here, please do not hesitate to contact us.

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