Clarity refers to the natural brilliance of the diamond and its ability to allow light to refract. The best way to measure the clarity is through the size of the stone, the number of blemishes, or inclusions. What are inclusions? These are nothing but internal irregularities. So, what are blemishes? It signifies external or visible imperfections on the stone. However, it is important to note that one cannot call them flaws but take them as the natural fingerprints instead.
Most of the time, the inclusions or blemishes are not visible to the naked eye. One needs to use a powerful loupe or microscope for spotting them successfully. As such, their presence visibly affects neither the beauty nor the appearance of the gemstone.
Inclusions signify non-diamond minerals, air bubbles, and cracks within the stone that have been with it right from the formation stage, deep inside the bowels of the earth. Small inclusions don’t mean much but larger ones will interfere with light dispersion diminishing the brilliance of the diamond. Besides this, large inclusions also affect the durability of the stone laying it prone to fracture by diminishing its resistance against impact.
Sometimes, colored inclusions may also be present influencing the overall appearance. The general rule of thumb is that more the inclusions in a diamond lesser will be its value.
Exterior surface imperfections are the blemishes of the diamond. It mostly includes chips, scratches, and pits. Other types may be the presence of lines, trigons, or nicks caused during the polishing and cutting processes. Depending upon size or location it is possible to polish away most of these. Re-cutting of diamond also helps in their elimination. Most blemishes do not have any effect on the overall appearance of the gemstone however, those present on the surface may affect its value or clarity.
In general, blemishes do not or rarely, have any impact on the structure and strength of diamonds.
Clarity Based Grading
Gemological Institute of America (GIA) has a globally recognized Grading System of diamonds in place for clarity assessment.
Here's a summary of its main GRADES.
- Flawless (FL): Extremely rare, with no blemishes/inclusions with 10x magnification
- Internally Flawless (IF): Quite valuable & rare, internally flawless, only surface blemishes present with 10x magnification
- Very Very Slightly Included (VVS1 & VVS2): Blemishes/inclusions with 10x magnification hard to spot for even skilled grader
- Very Slightly Included (VS1 & VS2): Minor flaws mostly invisible to naked eye but visible with 10x magnification
- Slightly Included (SI1/SI2): Blemishes/inclusions visible quite clearly with10x magnification
- I1/I2/I3: Blemishes/inclusions visible with the naked eye negatively impacting brilliance and transparency of the stone