Diamond Cloud Inclusions - Impact on Diamond Sparkle

The most spectacular diamonds are brilliant, fiery and dynamic. It is this great light performance that makes diamonds so beautiful and mesmerizing. The best diamonds almost seem to be alive, with personalities that change in response to each new lighting environment. On the other hand, nobody aspires to own a cloudy diamond! But there is a type of diamond inclusion called a “cloud”, and it is important to understand what impact diamond cloud inclusions have on light performance and diamond sparkle.

First, it is important to know that just because a diamond has a cloud inclusion does not make it “cloudy”. Cloud inclusions are very unlikely to have any appreciable impact on light performance in the higher clarity grades (VVS and VS). It is in the SI and below clarities that clouds are apt to be large enough or numerous enough to significantly impact the reflection and refraction of light among the diamond’s facets.

What is a diamond cloud inclusion? A cloud is really just an area of microscopic inclusions within the diamond. These areas can be large or small, dense or sparse. Depending on size and concentration and also on location, diamond clouds are capable of scattering light and diminishing the quantity and quality of light that is returned to the eye by the diamond. In most cases however, a cloud inclusion affects a very small area of the diamond and does no more to impede light performance than any other type of diamond inclusion such as a feather, crystal, grain line or twinning wisp.

The advantage that cloud inclusions have over feathers and crystals is that they are typically less noticeable. Because they are amorphous and often largely transparent, they tend to be more difficult to see, even with magnification. They are almost always invisible to the unaided eye. In many cases then, a diamond with a cloud inclusion may be more desirable than the same grade of diamond containing other inclusion types.

As stated earlier, the trouble with clouds starts in the lower clarity grades. SI2 and even some SI1 grade diamonds that have cloud inclusions are at risk of having diminished light performance. This usually takes the appearance of a very slight haziness which may not be readily apparent. Only when you compare it side by side with another diamond of similar quality that does not have clouds does the effect on light performance become noticeable.

With some advanced understanding of cloud inclusions and how to read a laboratory report, it is possible to identify those diamonds that are likely to be problematic and those that might in fact be advantageous. On a diamond report from GIA or AGS Laboratories, the primary grade-setting inclusion is listed first under “Key to Symbols”. So, if a cloud is the primary characteristic setting the clarity grade, it could be an indication of a possible issue. However, that is not always the case. Cloud inclusions are often dense yet small and discrete. Clouds of this type are unlikely to effect performance, even if listed first. Following this logic, if the clarity of the diamond is SI1 and the cloud is not listed first, it is very unlikely to impact performance. On the other hand, if the clarity grade is SI2 and the cloud inclusion is listed first, there is a possibility of compromised light performance.

Of more concern in terms of negative impact on light performance are diamonds in the SI clarity grades with a notation in the ‘comments’ field indicating “clarity grade based (or partially based) on clouds not shown”. These clouds have not been plotted as they tend to comprise larger areas within the diamond. In many cases these diamonds do suffer from diminished light performance.

Another factor that influences whether cloud inclusions will significantly alter a diamond’s light handling ability is location. If a significant cloud exists in a location within the diamond where light rays are concentrated it will tend to scatter more light. Such a key area is in the center of the diamond down towards the culet.

It must be noted in any discussion about diamond light performance that Diamond Cut Quality is hugely important to a diamond’s ability to handle light in an optimal way and deliver full brilliance, fire and diamond sparkle. So critical is this factor that ideal cut diamonds with clouds can be more beautiful than flawless diamonds that are not well cut. Other features such as internal graining and very strong fluorescence can also impact light performance creating a similar hazy or “milky” effect. These features will likewise be listed on the report.

In conclusion, diamond cloud inclusions are not something to fear. They normally have no appreciable impact on diamond brilliance. When considering diamonds of SI and lower clarities, the advice in this article will help you determine the possible impacts. Because there are many subtle but important issues when it comes to diamond quality, it is best to seek a certified diamond that has been analyzed by a reputable lab, and to consult with an expert who can act as your diamond guide and discuss with you all the issues that might be important to your complete satisfaction.