The 4C’s: colour, clarity, carat-weight and the most important, cut.
Colour: Diamonds range from colourless – the rarest and most valuable – to yellowish, with a spectrum of shadings in between. The only way to see the true colour of a diamond is to look at the unmounted stone through its side against a white background.
Clarity: The degree to which tiny natural marks called inclusions are present in a diamond determines clarity. A “flawless” diamond has no visible inclusions under 10-power magnification.
Carat-weight: This is the standard measurement for diamond size – and is actually the least important in determining the brilliance and beauty of a diamond. Every carat is divided into 100 “points” so a 50 point diamond actually weighs .50 carats (142 carats to the avoirdupois ounce).
Why is “cut” the most important characteristic?
When a diamond comes out of the ground it looks like a translucent pebble. Only when the diamond has been skillfully cut does it capture and release light brilliantly. Cut is the only one of the 4C’s completely under man’s control and the most important because it determines the amount of brilliance, sparkle and fire – the properties that make a diamond special.