Clarity is one of the 4Cs, but what does it actually mean?
In simple terms, how easy is it to see through the diamond? Can you see anything visible and how often does it occur? Imagine a pond, one day it's crystal clear the next it maybe muddy and murky then it could go back to clear with leaves floating on the top. Each day the pond will be different, much like a group of diamonds, there will be a contrast of different characteristics.
Natural diamonds form deep below the earth's surface. Diamonds are made up of carbon atoms which are exposed to a high amount of pressure and heat. As it is a natural process, there can be other 'ingredients' which create internal characteristics known as Inclusions as well as external characteristics called Blemishes. By assessing these characteristics we can gauge the price of the diamond. Examination is done under a 10x magnifying glass, a jewellers loupe, where the assessor can determine the number, size, type and location of the characteristics.
Below is a diagram of the different Clarity ratings of diamonds with the retrospective diamond according to the GIA (Gemological Institute of America).
Flawless (FL): No inclusions and no blemishes visible under 10x magnification
Internally Flawless (IF): No inclusions visible under 10x magnification
Very, Very Slightly Included (VVS1 and VVS2): Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
Very Slightly Included (VS1 and VS2): Inclusions are observed with effort under 10x magnification, but can be characterized as minor
Slightly Included (SI1 and SI2): Inclusions are noticeable under 10x magnification
Included (I1, I2, and I3): Inclusions are obvious under 10x magnification which may affect transparency and brilliance
Other organisations can have different descriptions but all should follow the same principles for each grading.
Flawless is very rare and as a result will increase the price of the stone, whilst Included will obviously decrease the value. But there are other factors that can also impact the price.
The diagram I found above makes it fairly obvious what the differences are when going down the chart, but when you look at a real stone you have to factor in the reflection, refraction and dispersion. All these things can 'blindside' you into thinking there is something which isn't there or it can hide certain inclusions.
Look at the image below, at first you may just see 8 diamonds. But when your eyes adjust you can start to tell the difference, between IF and I1 anyway! IF is crisp, clean and clear. Compared to the fuzzy and dull appearance of the I1. The I1 appears this way because inclusions can affect the brilliance of the stone, as they will interfere with the light that enters the stone. Using a computer image to tell the difference between the stones isn't impossible but it's not like having the actual stone in front of you.
Most diamonds will have gone through the cutting process with the cutter determining the best place to cut the rough stone, so it will have the least amount of inclusions or blemishes as possible, as they want to get as much profit as they can for that stone. If they can not avoid an inclusion, they will try and place them to the side (girdle) of the diamond, it is less visible here and if need be it can be covered by a metal setting with relative ease. But by avoiding certain inclusions, may reduce the total carat weight, which also reduces the amount they can sell the stone for.
In reality, a member of the public may not be able to tell the difference between the VS group or the SI group, this is when practice makes perfect. And that is something to remember when buying a diamond ring, who is going to tell the difference when it's on your finger? I also must stress that when a diamond is certified it is subjective. It's someone's opinion, albeit someone who looks at diamonds everyday, but if you send the same diamond to two different diamond labs, there is a chance they could come back slightly different.
I could go into this subject more, the different types of inclusions, how we can treat a stone to remove the inclusions and the step by step guide to assessing a diamond, but that's for another time!