A diamond is bought on four important criteria, known as the 4Cs – color, clarity, carat weight and cut. Each criterion plays an important role in determining the price and quality, however, you may place more or less importance on any of Cs depending on your personal decision.
Though a colorless diamond is considered most valuable, diamonds do have some degree f color in them, even though they may appear colorless.
It is almost impossible to have a diamond without impurities. Often invisible to the naked eye, these natural blemishes are categorized as — inclusions, which are internal, and blemishes, which are external. When the stone was being formed sometimes trace elements or minerals get trapped that result in inclusions that appear as feathers, clouds or crystals. Scratches and chips visible to the naked eye are known as blemishes.
While fewer such impurities will make the diamond more valuable the diamond, higher clarity does not necessarily mean that the diamond is more beautiful than a stone of a lesser clarity. But it will make a difference in terms of how the diamond is priced.
The GIA established a grading system to measure the type and size of these imperfections
FL, IF: Flawless, Internally Flawless. There are no inclusions — internal flaws — or blemishes — external flaws.
VVS1, VVS2: Very, Very Slight Inclusions. Hard to view such inclusions under 10x magnification. An excellent quality diamond.
SI1, SI2: Slight Inclusions. Inclusions are visible under 10x magnification and may not be visible to the naked eye when the stone is in the face-up position.
A good diamond value
I1, I2, I3: Obvious inclusions, which are visible to the naked eye.
The weighing unit for a diamond is Carat.