If you cannot tolerate imperfections, even those you cannot see, choose a VVS2 or better diamond. About 10% of all diamonds sold fall into this category.
The most popular range is the VS1-VS2 diamond. These diamonds appear flawless to the naked eye, and are a fraction of the price of a truly flawless diamond. Almost half of all diamonds purchased fall into this range.
The next most popular range is SI1, where the inclusions are usually not significant enough to impact the appearance of the diamond for the casual observer. Often, customers will opt for this clarity range in exchange for a higher cut or color grade. This combination often results in a beautiful, lively diamond with imperfections detectable only upon close inspection. In diamonds under 1 carat, the same can be said for an SI2 grade. In diamonds over 1 carat (where clarity is more important, and SI2 inclusions are often easier to detect), an SI2 is often half the price of a VS1 diamond. About one third of diamonds sold fall into the SI1-SI2 range.
If you are primarily concerned with size and price, I1 may be your best option. While the inclusions are visible to the unaided eye, many customers find it to be well worth the sacrifice for what it affords in size.
The larger the diamond, the easier imperfections are to detect; therefore Clarity becomes more important. For diamonds over 2 carats, a clarity grade of VS2 or higher is the safest bet for avoiding any signs of visible inclusions. In diamonds between 1 and 2 carats, clarity grades of SI1 or better will not have inclusions easily visible to the naked eye. In diamonds under 1 carat, clarity should be considered the least important of the traditional 4 Cs.
Brilliant-cut diamonds (such as round, princess, cushion, oval, pear, and marquise) hide inclusions better than step cuts (emerald, asscher). When purchasing a step-cut, move up one clarity grade (e.g. purchase a VS2 instead of an SI1 if you desire the lowest grade that has no visible inclusions).
If, while shopping for a diamond, you are ever given a clarity range (e.g. SI1-SI2) as opposed to a specific clarity grade, the diamond is not certified by GIA. The seller is only estimating the diamond's clarity using GIA terminology.Visit the Lumera Diamond Buying Guide for additional tips and advice.