I recently read some concerns expressed by vendors where consumers may be misunderstanding clarity red flags, particularly in regards to the comments section.

In my tutorial on diamond clarity, I brought up the red flag where you have a clean clarity plot for an SI quality diamond and then under the comments section, it states “clarity grade is based on clouds not shown”. Sometimes you will see a comment that says “additional clouds are not shown“.

Clouds that are not shown

The first thing I would like to clarify is that there is a big difference between a certificate stating that the clarity grade is based on clouds not shown and it stating that there are additional clouds that are not shown on the clarity plot.

The first comment is a warning sign if the diamond is of SI quality or lower. The reason for this is because the clouds need to be fairly bad in order for it to be the grade setting inclusion. You will notice in VS quality diamonds that usually the clouds are not the grade setting inclusions. In the case of the VS1 diamond in question, the clarity plot actually showed a cloud as the third severe clarity feature after a crystal and a needle. This is why the comment states that “additional clouds are not shown” rather than simply “clouds are not shown”.
 

 
What you can tell from this is that there may be one or more clouds that are not drawn on the clarity plot but these clouds are going to be less important than the one that is plotted and that as a collective of clouds, they are all less severe than the needle inclusion. Remember that a cloud is a group of tiny pinpoints so if each one is less severe than a VS sized needle, then you can be sure that the clouds are not going to affect the appearance of the diamond.

Also, make sure that when you are looking at an actual picture of a diamond that you see any signs of clouding. As with all clarity issues, there are degrees of severity. Furthermore, make sure that what you are not seeing are signs of strong or very strong fluorescence. You can see an example of a hazy/milky diamond caused by strong blue fluorescence in the basics tutorial on fluorescence.
 

 
Here is a picture of another diamond with a clarity grade based on clouds next to the cloudy diamond I identified in my tutorials. You can see that the diamond does not appear to be as cloudy. The problem is you can never be sure when you’re buying these kinds of diamonds online so I would recommend that you only do so if the price is excellent and that you are comfortable with any exchange procedures. It is always best to see these stones in person before you buy and make sure that you can view them in all kinds of lighting, especially natural light that is by a north-facing window.