Diamond clarity is arguably the second most important of the Four Cs of diamond rating (after Cut quality). The cut of the diamond can improve the clarity of the diamond even more, skillfully whisking out inclusions and flaws that otherwise might affect the flow of light through and around the stone. A brilliant cut is also adept at hiding inclusions behind brilliant facets. 

What is Clarity?

In general, a diamond should be as clear as water — but you should not be able to see through it in the way you would be able to see through a water droplet! The clearer a diamond is, the better the light will flow through the stone, and the more easily light is channeled, the better the clarity of the stone. Thus, it is easy to see that a high clarity diamond is more sparkly – and it is a diamond’s sparkle that makes it so attractive to those who like them. See more about the diamond clarity scale here, or consult the GIA or AGS website for full details.

How is Clarity Rated?

Clarity begins with F or IF which stands for Flawless or Internally Flawless. This means that when a jeweler examines the stone under laboratory conditions and greater than 10x magnification, there are no flaws or blemishes discernible to the naked eye.

The next grading is VVSI2, and VVSI2 which means very, very slightly included to the first and second degree respectively. This means that there is something visible under greater than 10x magnification but it is minute and only just noticeable to a jeweller who knows what he is looking for.

The next grading down, drops a V to become VSI1 and VSI2. At this point, using only 10x magnification is enough to spot the internal flaws in the stone, but it is still eye clean, which means that the flaws cannot be seen when looking at the stone without magnification. Often a less practiced jeweller will not be able to see the inclusions in a VSI1 stone without a lot of patience, time and sometimes advice from a more experienced guide. VSI2 stones are usually easier to categorise, having more noticeable flaws under 10x magnification, but still being largely eye clean.

All the diamonds mentioned above are likely to be highly desirable diamonds, twinkling beautifully and attracting good prices for their vendors.

We now move onto Slightly Included to the first and second degree, or SI1 and SI2. With SI1 diamonds, they are easily visible at 10x magnification, but tend to be eye clean, unless the cut is a spare clean cut like an emerald or Asscher cut which reveals sweeping planes of the diamond and can be unforgiving to even quite small issues.

Finally SI2 stones. These are usually the lowest clarity that commercial dealers will offer for sale, and they are often not eye clean – in fact, as many as seventy percent of the stones will have inclusions visible to the naked eye. However, the flaws are still relatively small, and your diamond will be structurally sound and will still sparkle delightfully, albeit not as symmetrically as could be desired.

So, should you buy a SI2 stone? In general, if the stone is pretty, and you can live with its flaws — and do bear in mind that up to thirty percent of SI2 included stones will be eye clean — then, yes, absolutely you should buy an SI2 stone if it suits your budget, rather than scrimping or overspending to buy a stone that will look only very slightly different to your SI2 bargain.