When considering the clarity of a diamond, I always begin with the advice that you do not want to have any inclusions that are easily visible to the naked eye. In practice, all flawless, VVS and VS diamonds will be “clean” to the naked eye. Most SI1 round diamonds and some SI2 round diamonds will as well. Using this as a starting point, you can decide how high on the scale you wish to be, understanding that it will cost more to move up to increasingly better grades. In my view, the best tradeoff for clarity versus the other factors of size, color and budget occurs in the range between VS1 – SI2. If the purity of the crystal structure is of exceptional importance to you, you should consider diamonds in the IF or VVS range. Otherwise, you will get a bit more for your money in the VS or SI range.
It is also important to note that emerald cut and asscher cut diamonds will more readily show any inclusions because of their step cut faceting pattern. The step cut faceting pattern results in a more window-like appearance of the diamond and allows you to see into the heart of the stone. As a result, any inclusions that are present may be more apparent to the eye. As a general rule, step cut diamonds should have a grade of VS2 or better, with the exception of the occasional SI1 stone that is otherwise clean to the naked eye.
