Last Updated on August 8, 2021
Surface graining is a term that refers to the presence of irregularities in the structure of your diamond. These affect the optical properties in various ways but to see the actual surface graining, you must view the diamond at high magnification.
The surface graining manifests as transparent lines which become semi-transparent when you view your diamond at different angles.
What is graining in a diamond?
The term ‘graining’ is most often used to describe ‘whitish’ or reflective areas that have an impact on your overall clarity grading that can only be fully determined at magnifications of more than you would see with a standard 10x view from a gemological microscope.
Graining is actually quite common in a lot of larger stones which have a high clarity and color rating, so the actual effects of graining have to be assessed individually by the jeweler who is grading the diamond.
How surface graining affects diamonds?
Think of surface graining as a collection of colored lines on the surface of the diamond. Surface graining affects diamonds by having an impact on their overall clarity.
Diamonds with an appreciable amount of surface graining are often described as being ‘hazy’, and if there is internal graining present as well than this too can worsen the clarity grade which the diamond will receive.
Is surface graining bad?
While surface graining does have the potential to affect the overall clarity grade of your diamond, in most cases they are going to be fairly insignificant. Surface graining might be present in a diamond and even a trained gemologist utilizing a 50x magnification might well have a difficult time locating the graining.
If graining is still a concern for you, many organizations such as the GIA do grade diamonds quite rigorously and can quite competently assess size and overall visibility of any internal or surface graining in a diamond that you are considering purchasing.
Just keep in mind that in most cases, the effects are going to be minimal and you’ll most likely never notice them at all!
How does a graining look in a rough diamond?
Surface graining is typically going to look like a series or collection of lines that will be transparent until you tilt the diamond at various angles in your magnified view. Internal graining can be similar, sometimes described as being rather like transparent to semi-transparent ‘creases’ like you might see in cellophane.
Heavy internal graining tends to have a reflective effect or even a whitening effect, and this may only be apparent at levels greater than 50x magnification and when the diamond is further viewed at assorted angles. Sometimes they might even resemble a ‘trapped raindrop’, white streaks, or even have a ‘vinegar and oil’ separation effect.
Most commonly, clarity-affecting graining will be similar to white or transparent streaks. In most cases these will be virtually undetectable but higher grading standards can be used to determine the approximate level of graining as-required.
Surface and internal graining are caused by irregular crystal growth and this is quite common, so some graining will not necessarily affect the overall value of your diamond.