How are Diamonds graded for clarity?
There are a number of factors that decide the value of a diamond but one of the most important is a diamond’s clarity. The classic definition of clarity is a gemstones ‘relative freedom from blemishes and inclusions’. In order to have a quick reference for the clarity of any given diamond jewellers often use diamond grading codes used by the GIA or IGI.
The Gemological Institute of America (GIA) uses the following grades for diamonds of different clarity:
Two categories of Very very slightly included VVS1/VVS2
Two categories of Very slightly included VS1/VS2
Two categories of Slightly included SI1/SI2
Three categories of Included I1/I2/I3
Where a diamond sits on this grading structure is decided by the prevalence of inclusions (internal irregularities in the stone) and blemishes (surface irregularities) which have an impact on the appearance of the diamond. Grading is often based on characteristics which do not have an impact the diamonds beauty or durability and are often only apparent under a microscope.
A diamond graded as flawless will have no flaws when viewed by naked eye or under 10x magnification. Flawless natural diamonds are extremely rare and extremely expensive as a consequence!
An internally flawless diamond has no inclusions but will have some surface blemishes not visible to the naked eye but that can be seen under 10x magnification. These surface blemishes can often be removed by re-polishing the diamond but this is rarely done.
Very very slightly included diamonds generally display ‘minute’ inclusions which are usually very difficult to see at 10x magnification and are not visible to the naked eye. Most stones you will see in jewellery stores are in the VVS1/VVS2 to VS1/VS2 range.
Very slightly included diamonds can have inclusions that are difficult (VS1) to somewhat easy (VS2) to see at 10x magnification. Any blemishes or inclusions on stones in this category are minor in nature.
Slightly included diamonds contain inclusions that are easy or very easy to see under 10x magnification although to the naked eye these stones will still look very attractive.
Included diamonds contain inclusions that are obvious under 10x magnification and these inclusions will frequently affect transparency and brilliance of the diamond in question. If the diamond falls into the lowest included category (I3) then it will often be deficient in clarity and durability with obvious blemishes as you look down through the table (large central facet at the top of a diamond) of the diamond.
Remember that there is a trade off in terms of the number of blemishes and inclusions that is acceptable in a stone. A lot of these characteristics add something unique to a stone like a human fingerprint is unique to each person and buying a lower grade stone means the stone you buy at any set price point can be larger. If the diamond still reflects light well and looks good under the naked eye buying a larger lower graded stone can be a very good option for many consumers.