Most jewelers who are trained in grading diamonds for clarity use the evaluation standards set by the Gemological Institute of America (GIA). Depending on the existence and visual appearance of internal characteristics (inclusions) and surface defects (blemishes), a diamond can be assigned one of the following grades:
- Flawless (FL)
- Internally Flawless (IF)
- Very, Very Slightly Included (VVS) – divided into two grades; VVS1 is a higher clarity grade than VVS2.
- Very Slightly Included (VS) – divided into two grades; VS1 is a higher clarity grade than VS2.
- Slightly Included (SI) – divided into two grades; SI1 denotes a higher clarity grade than SI2.
- Included (I) (formally "imperfect") – divided into three grades; I1 is a higher clarity grade than I2, which in turn is higher than I3.
Appraisers assign a clarity grade based on the overall appearance of the diamond. All jewelers, and even most consumers, are well-versed in the meanings of these grades. However, no two diamonds are exactly the same – inclusions and blemishes can be mapped out to create a unique “fingerprint” for a diamond, which is useful for tracking and certification purposes. So what considerations do appraisers use to assign a clarity grade when the flaws are infinitely variable? There are five factors: size, number, position, nature, and color. You can learn more about these factors and the ways they affect clarity grades in the infographic below.