Opal Brightness and Body Tone Guide
Opal Galaxy does not support the opal brightness and body tone grading systems. We will not provide an opinion on our opals regarding body tone or brightness scales.
We have come to this decision after over a decade in the industry trying to support the Opal Body Tone and Brightness grading systems. These grading charts complicate the industry invented by people. These complications take away from the nature of opals in that they are all unique to each other. We never really agreed with these charts and will no longer be supplying our opinions of body tones and brightness. An important thing to note is that these charts are not recognized by any official gemologist association or certification company (for example, GIA, GRS, etc.). Grading opals works against what opals are all about; each is unique. We believe they should not receive the same easy categorization as other colored gemstones, which all appear identical.
Another important point to consider is that grading opals is highly subjective and can vary from one person to another. As a result, achieving consistent accuracy is challenging since everyone has their own opinion on how opals should be graded. Furthermore, the brightness chart can add to the confusion for buyers. For example, some sellers use a chart where 1 represents the brightest and 5 the least bright, while others use the reverse system, with 5 being the brightest and 1 the least bright. This inconsistency makes the process even more difficult for those unfamiliar with the grading systems. We ask that people judge our opals for themselves without grading them.
Our photos and videos accurately show how the opals look in person with light exposure.
Opal Body Tone
There are four main types of Australian Opal that people are concerned with, including body tone. These are Black Opal, Dark Opal or Semi Black Opal, White Opal, and Crystal Opal. To identify the shade of an opal’s body tone, examine the color of the potch on the back or the transparency in the crystals. In black and dark opals, the shades can range from jet black to lighter black or grey, as the potch’s shade varies between opals.
Crystal opals are transparent and usually do not have any or much potch on the back. If some potch is present and the opal remains transparent, it qualifies as a crystal opal. If the shade of the transparency is a lot darker with deeper colors in the opal, then this is a good indication that the opal is either a black crystal or dark crystal opal.
Light will pass through a crystal opal
 An example of a black crystal opal
White opals have white potch instead of black or dark potch.
Boulder opal and sandstone crystal boulder opal typically lack body tone judgment due to their distinct and individual characteristics. The ironstone usually gives good, intense colors to the opal’s face. An exception to this is black boulder opal, which is a much darker ironstone host rock with higher manganese levels.
For a person to know the grading level of body tone in an opal, it should not be a determining factor in purchasing. This is because there are low and high grades of opals, which also influence how an opal looks and is valued. With body tones, we will always classify the type of opal (e.g., Black Opal, Dark Opal, Crystal Opal, etc.); however, we will not provide a grading based on the opal body tone chart.
Opal Brightness
If an opal is well polished (like all of the opals we sell), it is the brightest that it can be. The brightness of opal comes from several determining factors. Then, there is exposure to light, play of color, specific colors in the opal, pattern, and the amount of potch (colorless opal) in the opal.
We ask that people judge our opals by how they look in our photos and videos; these are all very true to how the opal looks in real life with light exposure.