Marking of precious opals

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Marking of precious opals

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Marking of precious opals

Black Opal, Body Tone N1, brilance 4, Brightnnes 1

When buying expensive opals, especially from Australia, you will come across various designations. In this article you will find the necessary information about what the label means and what it is used for.

Who designed them and what are they for?

All of these designations were designed and created by the Australian Opal Association. They help consumers find out more quickly how good the opal is. According to a photo on the internet, it is often not known how opal can look in other lighting conditions, such as the intensity of colors. These labels help the customer to get a more accurate idea of quality. There is no machine for determining these criteria and everything is determined with the naked eye, so these designations are for information only, it is more of a guide.

Which label is most important?

1. The most important and valuable feature of precious opals is the play of colors, ie brilliance or the newly used table for brightness (Brightness)

2. Color pattern or predominant color (Pattern)

3. Body Tone

(This order is not prescribed in any way)

1A. Color brilliance

The most important feature of expensive opals is the brilliance of the colors. Simply put, the brightness or intensity of the color change. A table with a scale from 1 to 5 is used for brilliance, where 5 is the highest possible brilliance. For more accurate determination, intermediate steps such as 4.2, 3.8, etc. are often used.

More accurate comparison:

Brilliance 1 - 3

Such opals have almost no color change, the intensity of coloration is not visible even under artificial lighting. Often such low brilliance is not even mentioned. This is already clear from the photos of opal and the price of opals is very low

Brilliance 3 - 3.5

The colors in the opal are gloomy, as if drowned, under artificial lighting the color intensity improves a little, but it does not shine

Brilliance 3.6 - 3.9

The colors are more visible, they do not shine

Brilliance 4 - 4.5

The colors are already beautifully visible even in poor lighting conditions, under artificial lighting they will already light up

Brilliance 4.5 - 4.9

Colors are clearly visible even in bad conditions, bright under artificial lighting, strong, clear colors, undisturbed

Brilliance 5

Maximum. Opal shines even in very bad conditions. Bright, strong, vibrant colors. For expensive opals from Australia, the number 5 is rare and I personally use it only rarely. The most common now is the number 5 for expensive opals from Ethiopia.

1B. Brightness

A new table for determining the brightness of opal, which is often used in Australia and is gradually replacing the scale of brilliance. The Opal Brightness Guide helps you assign a value for how clearly opal is visible to the naked eye.

Assess brightness on a scale of B1-B7

For assessment, the opal is placed on a table and assigned a value according to the eye. Opals with a brilliance above 3.5 are used for this method

The first table used for opals also has doublets and triplets.

2A. Colors

Order from the most valuable color:

1. red
2. purple, magenta
3. orange
4. yellow
5. green
6. blue

Red is the most sought after and most valuable. In the case of black opal, especially N1-N3, the violet and magenta colors are evaluated in the same way. Other highly sought-after opals have a color combination. If the opal has only a blue color and an interesting pattern, the price increases, even if the color is not so attractive.

2B. Pattern

Another important criterion is the color pattern. Their name is derived from a shape that resembles. For example, the Chinese Writing Pattern. The arrangement of colors in opal resembles the Chinese script. Popular Floral Pattern resembling a flowering meadow.


One of the most valuable color arrangements for Australian opals is the so-called Harlequin - a repeating pattern of colors and bright glowing. This is a very rare pattern and can also be found in expensive opals from Ethiopia and Boulder opals. The word Harlequin was a French word used in the 16th century to describe a comedian in the opera "commedie dell'arte". This character wore clothes with irregular patterns in bright colors. According to the arrangement of these colored spots, we further divide the harlequin into other patterns, which we will describe in one of the other articles being prepared.

Examples of other patterns:

Mackerel Pattern - Beautiful and rare rolling patterns
Patchwork - As the name suggests, these are multiple related patterns in one opal
Pinfire - Small bright patterns of mostly different colors. Scattered all over the opal


One of the most popular designs for expensive opals from Ethiopia is the naturally shaped line with inclusions, known as the Honeycomb. This sample is very rare in any other type of opal.

Ethiopian opals have vivid translucent colors and patterns that are strikingly clear and visible to the naked eye.

They are prized for their bright flashes of fiery colors. The brighter and more intense the color, the higher the price of opal.

3. Body Tone

The shade is determined by the scale. Here it is determined whether it is a black opal (Dark Opal), a dark opal (Dark or semi-black opal) or a crystal opal

Black Opal - N1-N4 - Lightning Ridge, Mintabie, rarely Coober Pedy (Australia)

Dark opal (Dark opal, semi-black) - N5-N6 - Lightning Ridge, Mintabie, Coober Pedy (Australia)

Crystal opal - N7-N9 - Coober Pedy and most Australian deposits, Precious opals from Ethiopia

What to watch out for

Beware of some sellers who sell Black Opal from Ethiopia. Mostly it is a modified classic crystal Ethiopian opal. It is treated with so-called smoke (Smoked Opal), they are called black opals due to the dark shade that was achieved by smoke. This label is incorrect and is considered an advertising ploy.

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