They are: Cut, Color, Clarity and Carat weight.
Each of the ‘C’s” plays its role in producing the most beautiful stone to create Fire and Scintillation. They also figure into the cost or it’s value.
Cut: has been debated for centuries. Which shape is most preferred, which produces the most fire, which is the most elegant on the wearer’s hand. As times change and styles evolve different cuts of diamond have come in to and fallen out of favor.
Though the eternal favorite cut is the Round Brilliant Cut. There have been millions of dollars spent on studying which angles and other elements create the most brilliant diamonds. Returning Fire back to the eye of the beholder.
Color: is a measure of the absence of color or how white is the stone. Of course there are fancy colored diamonds, but those are measured on a different scale, with different terminology.
In a laboratory sets of “Master Stones” are used by the gemologists. The subject stone being compared to the different master diamonds each representing a different color on the color scale. In this way each diamond is judged by a benchmark making the grading consistent from day to day and year to year.
Clarity: is measuring the observable “fingerprints” nature left in a diamond. Gemologists use a magnifier called a Loupe. All jewelers loupes magnify at 10X. There are a few kinds of clarity characteristics or inclusions in a diamond. Some are dark color called Crystals and others are clear or white called Clouds The size, amount, and orientation to the top of the stone determine the clarity.
Carat Weight: is the amount a diamond weights on a special scale. A carat is 1/5 of a gram. Diamonds measured in Carats and then subdivided into Points. Where 100 points equals 1 Carat. Just as 100 pennies equals 1 dollar.