Cut
This refers to the way a diamond is cut and how many facets it has (planes of polished faces). It is one of the most important of the 4 Cs. If a diamond is well cut, then it can will have an amazing fire (that is, brilliance and sparkle). A diamond's cut also determines the amount of light that returns to the eye after it has entered the diamond. In other words, if a diamond is cut too deep or too shallow, then light leaks out of the diamond pavilion, and lose its brilliance.Color
Diamonds may appear colorless, but they may actually have subtle tints of yellow tones. Diamonds are graded according to the Gemologic Institute of America (GIA) color chart, which measures the degree to which a stone approaches colorlessness: The more colorless the diamond, the rarer and more expensive. The color chart begins with grade D (colorless), and moves through the alphabet. D, E, and F stones are the most expensive.Clarity
Clarity is an indication of a diamond's purity. Almost all diamonds contain naturally occurring small blemishes called inclusions, which can be seen under powerful magnification. These blemishes can occur as a natural part of the stone, during the cutting and polishing process, or due to wear.In general, diamonds with fewer and smaller inclusions are more brilliant, assuming that the color and cut are the same. Diamonds with no inclusions (less than 1% of all diamonds) are graded F or IF (flawless). While diamonds with the fewest inclusions are graded VVS1 or VVS2. The fewer the inclusions, the more valuable the stone.