The 4 C’s stand for Carat, Clarity, Color and Cut.
Clarity refers to how clear a diamond is and is based on how many inclusions are inside the diamond. Inclusions can include minute crystals, growth patterns, tiny enclosed fractures, etc. Clarity is measured on a scale from IF (internally flawless) to I2 (included 2). The clearer a diamond is the rarer and thus, the higher the price.
Color refers to the color of a diamond. Diamonds tend to have a yellowish or brownish tint. The scale starts at D (colorless) and goes all the way down to Z (noticeable color). Most diamonds we see in the market are in the D-I range.
Cut refers to the cut of a diamond and is the most overlooked but possibly the most important! Cut is the only contribution by man, while all others are naturally occurring. Cut can really make or break the appearance of the stone. If a diamond has excellent proportions, symmetry and angles it is going to have optimal light return and be very sparkly. If a diamond has poor angles, poor symmetry and poor polish, it will appear dull and dark.