Carat Weight

Carat Weight" is simply the weight of the diamond. By definition, 1 carat is exactly 200 milligrams. Since most diamonds sold in the jewelry industry weigh less than 1 carat, the carat is usually subdivided into "points." There are 100 points in 1 carat, so that a diamond weighing 3/4 carat would be a "75 point diamond." In summary:

1 carat = 200 milligrams = 100 points

Carat weight is not a factor which denotes diamond quality. It purely denotes the size of a diamond, by its weight. Obviously it also affects the value or price of a diamond, because consumers tend to prefer bigger rather than smaller diamonds. Large diamonds are also rarer than small diamonds. Because there is higher demand and lower supply for large diamonds, they command higher prices. Often people talk about the size of diamonds. Size in this context really means weight, as large diamonds will normally weigh more than small ones.

The Federal Trade Commission has strict guidelines about the range of carat weight that a fraction can represent. The chart below outlines acceptable ranges for carat weights expressed as fractions.

• 1/4 carat total weight may be 0.21 to 0.29 carats
• 1/3 carat total weight may be 0.30 to 0.36 carats
• 1/2 carat total weight may be 0.45 to 0.59 carats
• 3/4 carat total weight may be 0.70 to 0.84 carats
• 1 carat total weight may be 0.95 to 1.10 carats
• 1 1/4 carats total weight may be 1.20 to 1.29 carats
• 1 1/2 carats total weight may be 1.45 to 1.55 carats
• 2 carats total weight may be 1.95 to 2.05 carats

When diamonds are mined, large gems are discovered much less frequently than small ones, which makes large diamonds much more valuable.

In fact, diamond prices rise exponentially with carat weight. So, a 2-carat diamond of a given quality is always worth more than two 1-carat diamonds of the same quality.

The carat weight of a diamond is a major factor in its price, but the cut, color, and clarity will also affect the price greatly. A 1/2 carat (0.50 ct.) diamond solitaire with high color and clarity ratings may cost more than a 3/4 carat (0.75 ct.) diamond solitaire with lower color and clarity ratings. Because large diamonds are much rarer in nature than small ones, diamond value increases exponentially for certain thresholds of diamond carat weights. A 1 carat diamond will cost more than twice as much as a 1/2 carat diamond of comparable quality.

As diamond carat size increases, both the diameter and the depth of the diamond increase. This is why a 1 carat diamond (approximate 6.5mm diameter) does not look twice as wide as a 1/2 carat diamond (approximate 5mm diameter). When choosing a diamond size, keep the size of the wearer in mind. Diamond studs with an individual diamond weight of 1/2 carat each may be more suitable on very small earlobes than diamond studs of 1 carat each. Likewise, a 1 carat solitaire will appear much larger on a size 4 finger than a size 8.

More information on the 4c's of a diamond