Diamond Clarity Guide
One of the "4 C's" of diamonds, clarity ratings are how jewelers describe the degree of transparency of a stone. It's also an important factor in the price of the diamond - stones with fewer inclusions will fetch higher prices. Good clarity is much more common in small diamonds than in larger ones, however poor clarity is also more noticeable in a large stone. Clarity flaws are also more obvious in stones with large surface planes (such as emerald cut/step cut diamonds) than they are in a brilliant cut diamond.
The standard clarity ratings used by the GIA (Gemological Institute of America) are as follows:
FL - (Flawless) A completely flawless stone - very rare.
IF - (Internally Flawless) Essentially a flawless stone, but there are some tiny external flaws on the stone.. These can generally be removed by polishing. Also very rare.
VVS1 and VVS2- (Very Very Slight) Extremely small inclusions which are difficult even for an Flaws which can only be expert gemologist to spot when using a 10x (or stronger) loupe or microscope. If the flaws can be seen from the top of the diamond, it is a VVS2, flaws in a VVS1 can only be seen from the pavilion (bottom) of the stone. Some VVS1 flaws can be removed by re polishing the stone.
VS1 and VS2 - (Very Slight) Flaws which can be seen under 10x magnification, but which aren't immediately obvious. It usually takes a trained diamond grader to discern flaws in a VS1.
SI1 and SI2 - (Slight Inclusions) - Flaws can be readily seen with 10x magnification of the stone.
The European Gemological Laboratory (EGL) has an additional designation: SI3. SI3 stones are somewhere between SI2 and I1, with flaws which can be seen without magnification but which are not immediately obvious.
I1, I2 and I3 - (Included) Flaws can be seen with the naked eye. These are the least expensive diamonds, often used as tiny accent stones or in affordable fashion jewelry.
Jewelers in India use the designations P1, P2 and P3 in place of I1-I3.
The pattern of these flaws are what make diamonds unique as snowflakes and provide a means of identifying a particular stone. Flaws are described by their number, location (position), size and nature (the type of flaws)
Types of flaws:
Flaws come in many varieties. The most common diamond flaws are pinpoints - small white dots on the surface of the stone. With a little practice, you can easily learn to spot these yourself.
Other frequently seen flaws are carbon (a black dot), clouds (a cloudy area within the diamond), crystals (visible crystals within the diamond) and feathers (cracks within the stone - small ones are generally harmless but large feathers can affect the structural integrity of your diamond). Additional interior flaws include bruises, cavities, chips, cleavage, knots, needles, or internal graining. The exterior of a diamond can have abrasions, pits, polish lines and marks, scratches, surface graining, or an extra facet.
Artificial enhancement of diamond clarity:
There are several ways to artificially remove certain flaws in a diamond - this is called clarity enhancement. The GIA does not certify clarity-enhanced stones. Also, sometimes fractures in a diamond can be filled, but this is not a permanent fix and fracture-filled diamonds are susceptible to heat damage. The GIA will not grade these stones and reputable vendors will disclose to their customers if a diamond has been enhanced in this manner.
Always buy the best you can afford, but if cost is a concern don't be afraid to sacrifice quality on small diamonds in your setting in exchange for a better center stone.
Additional Resources:
GIA Library Clarity Scale FAQ
EGL USA Clarity Scale