Cut, Carat, Colour and Clarity, the 4 C's, the universal language that will help you pick out the right diamond for your engagement ring.
The term "cut" has two meanings, one is the diamond's shape, the other is the quality, determined by its proportions, symmetry and polish.
The top-selling diamond cut shape is the round brilliant which is typically used in a conventional engagement ring. If tradition is not what you're after, the marquise, pear, oval, hexagon or fancy rose cut shapes are great picks to satisfy the alternative mind.
The cut of a diamond is considered to be the most important factor with respect to its beauty. The cut determines how the light is reflected and dispersed within a stone.
The colour of a diamond is actually evaluated based on the absence of colour. The Gemological Institute of America (GIA) uses a 12 letter scale of D to Z where the diamond on the lower end of the scale (D) will have the least amount of colour (a.k.a. colourless) and the higher end of the scale (Z) has deeper tones (and enters the fancy colour spectrum).
Of the 4 C's, the carat weight is the easiest to understand. A diamond's weight is measured in carats. The carat is subdivided into 100 equal parts called 'points.' One point equals .01 carat or 1/100 carat.
The clarity of a Diamond's internal characteristics known as inclusions or external characteristics known as blemishes. Diamonds without inclusions or blemishes are rare; however, most characteristics can only be seen with magnification.
While the above is the standard, its important to note that diamonds come in raw form before they are cut and polished. The raw uncut diamond has its own exquisite character. People have now started appreciating the beauty of organic rough diamonds and raw diamond engagement rings are gaining popularity among those who want something really special.
Hope this gave you a bit of clarity on the phenomena of diamonds.