Natural diamonds form as a result of carbon being exposed to immense heat and pressure deep in the earth. During this process, small crystals can become trapped in the diamond causing irregularities in the structure of the diamond. When we talk about clarity, internal characteristics are called ‘inclusions’ and external or surface characteristics are called ‘blemishes’. The size, number, location, nature and colour of any blemishes and inclusions.
Most blemishes and inclusions are not visible with the naked eye, but are visible through a jewellers loupe or a microscope. In fact, it is difficult to detect inclusions in diamonds graded VS2 or SI1, so if may be worth considering a diamond of a better colour and lower clarity if you're on a budget.
The GIA Diamond Clarity Scale has six categories, some of which are divided, for a total of 11 specific grades.
- Flawless (FL)No inclusions and no blemishes visible under 10x magnification
- Internally Flawless (IF)No inclusions visible under 10x magnification
- Very, Very Slightly Included (VVS1 and VVS2)Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
- Very Slightly Included (VS1 and VS2)Inclusions are observed with effort under 10x magnification, but can be characterized as minor
- Slightly Included (SI1 and SI2)Inclusions are noticeable under 10x magnification
- Included (I1, I2, and I3)Inclusions are obvious under 10x magnification which may affect transparency and brilliance
The diamond grading system was developed by the Gemological Institute of America (GIA). The short video below explains diamond clarity.