Carat Weight
Larger diamonds not only cost more, but they cost more per carat!

Definition: Carat (abbreviated ct.) is the standard unit of measurement for the weight of a diamond. One carat equals 0.200 grams or approximately 0.007 ounces. To provide a frame of reference - a very small plastic paper clip weighs about a carat.

  • Diamonds are weighed to a thousandth (.001) of a carat, and then rounded to the nearest hundredth, or point. A diamond weighing 50 points is called ½ carat; one that weighs 75 points is called ¾ carat.
  • Diamonds weighing more than one carat are measured in carats, plus two decimal places for the points. A diamond weighing 1.07 carats is one carat, plus 7 points.

Magic Carat Weights

When pricing diamonds, remember that some carat weights are considered 'magic'. A 1.00 carat diamond will cost considerably more than one weighing 0.99 carat, even though there is virtually no difference in size. Other examples of magic weights are: ½ carat, ¾ carat, 1.50 carats, 2.00 carats.
Magic Carat Weights
Half carat 0.50 ct.
Three-quarter carat 0.75 ct.
Carat 1.00 ct.
One and a half carats 1.50 ct.
Two carats 2.00 ct.
Carat Weight And Value

One interesting consideration is the relationship between carat weight, rarity and value. Some are surprised to find that a 2.00 ct. diamond can be worth more than three times a 1.00 ct. diamond of similar clarity, cut and color.

The reason that values increase so rapidly with greater carat weight is really simple: larger diamonds are much rarer than small ones, and rarity drives up the price. So a larger diamond not only costs more, but it also costs more per carat, when compared to a comparable diamond that weighs less.

Let's look at the comparative value of round brilliant cut diamonds of the same quality (VS1 Clarity, F color, Ideal proportions) at different carat weights:
Carat Weight
0.50 ct.
1.00 ct.
1.50 ct.
2.00 ct.
3.00 ct.
Price Per Carat
$4,400
$7,800
$10,000
$12,500
$15,300
Est. Value of Diamond
$2,200
$7,800
$15,000
$25,000
$45,900