A diamond is the hardest substance known to man and can only be scratched by another diamond. Because it is so hard it is slightly brittle and can chip if struck hard. There are extreme methods of treating diamonds such as lasers and gamma ray bombardment that are used to change their properties. Other than these extreme methods your diamond will never change so it is important to know what you are buying.
The 4 C's
A diamonds value is determined by its rarity and the craftsmanship used to fashion the finished diamond. The rarity is graded by Clarity and Color, and Carat. The craftsmanship is graded by Cut.
Carat refers to the weight of a diamond. One carat is equal to .2 grams. Diamond weight can be referred to by fractions ( 1/2 ct.) or by percent (.50 ct.). When a diamond is referred to by percentage, you will hear a .50 ct. diamond called a fifty point diamond. Because diamonds come in all sizes and are very valuable using the percentage method to refer to a diamond is more accurate. A .48 ct. diamond and a .52 ct. diamond are both considered a 1/2 ct. It is important to understand that all diamonds that weigh 1 ct. are not the same diameter. Because carat is only a measure of weight.
A diamonds value increases disproportionately from the size of the diamond. There are many more rough diamonds found that a 1/2 ct. diamond could be cut from than a 1 ct. diamond. Diamond cutters always cut the largest and finest diamond they can from a piece of rough diamond. Therefore a diamond that weighs 1 ct. cost more that twice the price of a 1/2 ct. diamond. The price for large diamonds over 3 ct. sky rocket in price.
Clarity refers the the presence of inclusions or imperfections in a diamond. Diamonds are formed deep beneath the surface of the earth over millions of years. Because they are part of nature they are never perfect. Diamonds will have irregularities in their crystal structure. These irregularities will vary greatly in quantity, size, shape, and color. Jewelers grade diamonds under a 10 power microscope. The more, larger, and noticeable the inclusions in a diamond are the less the diamond will be worth. Some diamonds will be flawless under 10 power. Some diamonds will be so flawed that you will not be able to see through them. The jewelry industry and the Gemological Institute of America (GIA) have come up with a grading system to quantify the extent a diamond is included.
Color refers the actual body color of a diamond and not the colors that are reflected by the diamond. GIA has developed the following system for quantifying the amount of color contained in a diamond.
D,E,F are colorless - G,H,I,J are near colorless - K to W are light colored - X,Y,Z are fancy colored
Cut refers to the craftsmanship used to fashion a rough diamond into a finished jewel. Diamonds are fashioned into many different shapes.
A rough diamond as it is found in the ground.
Diamonds after a craftsman (Diamond cutter) shapes them
The brilliance a diamond shows is a property of the cut. When cutting a diamond it is extremely important that the cutter fashions the diamond to exacting proportions. The inside of the diamond than acts as a series of mirrors that reflects all the light that enters the top of the diamond back out the top. A diamond that is cut near perfectly can cover up small inclusions and slight color. A diamond that is flawless and colorless but cut poorly will look unattractive.
What Diamond is the Best for Me?
We have always said "Buy the biggest and prettiest diamond you want to afford". It is that simple.
You may not care if a diamond has a little inclusion that can be seen by young strong eyes or that the color is not perfect. You may want a larger diamond. On the other hand you may want a smaller diamond that is more perfect. There is no right answer for everyone