The Essential 7C's
When diamonds are formed, deep underground and under extreme pressure and heat, imperfections in the crystal structure can form and mineral impurities become trapped inside the stone.
The size of these impurities and imperfections determine the clarity grading of a diamond. Diamonds without such impurities are very rare.
The grading scale starts from Flawless / Internally Flawless (FL/IF), Very Very Slightly Included (VVS1/VVS2), Very Slightly Included (VS1/VS2), Slightly Included (SI1/SI2) to Included (I1, I2 and I3). 77 Diamonds does not sell diamonds below SI2 as they are not considered suitable for jewellery. Generally, diamonds below a VS2 grading are likely to have visible inclusions to the naked eye however this is on a stone by stone basis.
IF
Internationally Flawless: These rare high clarity diamonds are 100% flawless inside the diamond with no blemishes or inclusions.
VVS1
Very Very Slightly Included 1: There will be one minor inclusion within a diamond of this grade but only visible under 20x magnification or more.
VVS2
Very Very Slightly Included 2: There will be minor inclusions within a diamond of this grade but only visible under 20x magnification or more.
VS1
Very Slightly Included 1: Diamonds of this clarity will have several inclusions that are only visible with magnification of 10x but remain clean to the naked eye.
VS2
Very Slightly Included 2: Diamonds of this clarity will have several groups of inclusion that are only visible with magnification of 10x. A small percentage of these are not eye clean.
SI1
Slightly Included 1: Only 50% of diamonds of this clarity have no visible inclusions so it is important your selected diamond is eye clean.
SI2
Slightly Included : 85% of diamonds of this clarity have some form of visible inclusion or blemish to the naked eye.
I1
Included 1: Due to the high level of inclusions here, we do not recommended this clarity grade for diamond jewellery.
Expert tip 1
As magnification is needed to see impurities in diamonds witha VS1 grading or higher, a choice of VS1 or higher is a subjective quality choice which goes beyond what can be seen to the unaided eye. Larger Diamonds with these higher grades are much rarer and therefore command greater pricing premiums, and also tend to perform better as an investment.
Expert tip 2
Although SI1 and SI2 are in general not eye clean, the impurities may be light in colour or scattered and so in up to 20% of cases, SI1 graded diamonds may appear to be eye clean. That number falls to just 5% for SI2s.
There are many different types of impurities, but feathers and crystals are the most common forms of inclusions found in diamonds.