The Larger a Diamond, the More Rare
Larger diamonds are found relatively infrequently in nature, which places them at the rarist level of the Diamond Quality Pyramid. What also makes a bigger diamond so desirable is that it shows off a stone's fine color and cut, and therefore its brilliance, to its best advantage.
A diamond's size is measured in carat weight, and each carat is equal to 100 points. A .75 carat diamond is the same as a 75-point diamond or a 3/4 carat stone.
The More Pure the Color in a Diamond, the More Rare
Diamonds are graded by color, starting at D and continuing through the alphabet. Truly colorless stones, graded D, treasured for their rarity and value, are highest on the Diamond Quality Pyramid.
While many diamonds appear colorless, they may actually have subtle yellow or brown tones and these color grades include P and Q. Although still beautiful, they will be less rare and therefore less valuable. To appreciate the simple beauty of each individual stone, you should compare diamonds side by side with a jeweler.
"Fancy" diamonds -- in well defined colors that include red, pink, blue, green and canary yellow -- are highly prized and particularly rare.
The Purer a Diamond, the More Brilliant
The greater a diamond's clarity, the more brilliant, valuable and rare it is -- and the higher it is on the Diamond Quality Pyramid.
Virtually all natural diamonds contain identifying characteristics, yet many are invisible to the naked eye. Under the scrutiny of a jeweler's 10x-magnifying loupe or microscope, natural phenomena -- called inclusions -- may be seen. These are nature's birthmarks, and they may look like tiny crystals, clouds, or feathers.
Diamonds categorized as internally flawless reveal no such inclusions. Flawless stones are at the peak of the Diamond Quality Pyramid and are treasured for their rarity and beauty. Diamonds with very, very small inclusions are graded as VVS1 or VVS2. The larger the inclusion, the lower the grade and the less rare the diamond. Inclusions that can be seen with the naked eye are graded I1 or I3.
The number, color, type, size and position of surface and internal birthmarks affect a diamond's value. Major inclusions can interfere with the path of light that travels through a diamond, diminishing its brilliance and sparkle and therefore its value. The clarity categories are:
Shapes of Stones
Marquise: oblong shape that is pointed at the top and bottom
Pear: round shape at the bottom and pointed at the top
Heart: the shape of heart
Round: traditional cut also known as a brilliant cut
Oval: oblong shape that is rounded at the top and bottom
The Better Cut a Diamond, the More Brilliant
A well cut or faceted diamond, regardless of its shape, scintillates with fire and light -- offering the greatest brilliance and value.
While nature determines a diamond's clarity, carat weight and color, the hand of a master craftsman is necessary to release its fire, sparkle and beauty. When a diamond is cut to good proportions, light will reflect from one mirror-like facet to another and disperse through the top of the stone, resulting in a display of brilliance and fire.