Diamond Clarity
Clarity is a measure of internal structural imperfections called "inclusions". Grades of clarity, which are mostly those used by Gemological Institute of America (GIA), are:
- FL - "flawless" in that no inclusions are visible under 10 times magnification
- IF - "internally flawless" with no inclusions visible under 10 times magnification, only small blemishes
- VVS1 and VVS2 - "very very small" inclusions that are difficult to see under 10 times magnification. VVS1 is a better grade than VVS2.
- VS1 and VS2 - "very small" inclusions and visible under magnification but invisible to the naked eye.
- SI1 and SI2 - "small inclusions" that can be noticeable to the naked eye, if you know where to look.
- "SI3" is a grade sometimes used in the industry, originally popularized by the European Gemological Laboratory (EGL) Los Angeles grading office. While theoretically a range including lower SI2 and upper I1, it's commonly used to mean I1's which are "eye clean", that is, which have inclusions which aren't readily visible to the naked eye. Neither the GIA nor the American Gemological Society (AGS), the most reputable well known US labs, assign this grade.
- I1, I2 and I3 - "imperfect" and visible to the naked eye. For I3, the inclusions impact the brilliance of the diamond and are large and obvious.
All grades reflect the appearance to an experienced grader when viewed from above at 10x magnification, though higher magnifications and viewing from other angles are used during the grading process. In "colorless" diamonds, dark inclusions will tend to create the greatest drop of clarity grade. In other colors pale inclusions may have greater relief (may stand out more) and may cause a greater drop in grade.
Beyond the clarity grading terms, other considerations include the type, size and location of the "inclusion". Inclusions near or on the surface may weaken the diamond structurally. Depending on where the inclusion occurs in the cut diamond and how it is to be used, it may be possible to hide the inclusion behind the setting.
Laser "drilling" involves using a laser to burn a hole to a colored inclusion, followed by acid washing to remove the coloring agent. The clarity grade is the grade after the treatment. The treatment is considered permanent and both the GIA and AGS will issue grades for laser drilled diamonds. Reputable vendors should disclose that laser drilling has been used.
Clarity can also be "enhanced" by filling the fracture much like a car windshield crack can be treated. Such diamonds are sometimes called "fracture filled diamonds". Reputable vendors must disclose this filling and reputable filling companies use filling agents which show a flash of color, commonly orange or pink, when viewed closely. There is a significant price discount for fracture-filled diamonds. The GIA will not grade fracture-filled diamonds, in part because the treatment isn't as permanent as diamond. Reputable companies often provide for repeat treatments if heat causes damage to the filling. The heat required to cause damage is that of a blowtorch used to work on settings, and it is essential to inform anyone working on a setting if the diamond is fracture-filled, so they can apply cooling agents to the diamond and use greater care while working on it.