Diamond Avenue



Gemological Characteristics - The Four C's - Carat (weight)

The term "carat" is derived from the seeds of the carob tree.  The seeds of this tree are very nearly the same in weight, thus in the ancient world, they became the ideal weight unit for gem traders to use when doing business.
The weight of one carob seed later became standardized as (1) carat or 1/5 of a gram or .007 ounces.

Because diamonds come in many sizes, a carat had to be broken down into smaller units.  These units were named"points." There are (100) points in (1) carat, and with this as a measure, 1/4 carat equals (25) points, 1/2 carat
equals (50) points, and 3/4 carat equals (75) points.

Carat weight is the most prominent characteristic in determining a diamond's value.  However, as discussed in the General Advice section, two diamonds of equal carat weight and quality can have very different prices based on
other factors such as proportion. For example, a (1) carat diamond can have an "ideal" diameter of 6.5 millimeters, while a second (1) carat diamond of the same quality could have a 5.5 millimeter diameter.  Because the second
diamond is (1) millimeter smaller in diameter (not ideal), it would most likely have a lower value than the ideal diameter diamond.  This will be discussed in greater detail under the fourth characteristic: cut.

Even small diferences in carat weight can greatly affect the value of a diamond. For example, a small (1) point difference such as between a diamond with a carat weight of (1) carat and another with a carat weight of (99) points
will cause a significant difference in value. The (99) point diamond falls in a lower category or class than the (1) carat diamond and as a result, the smaller diamond's value may be considerably less.

It is interesting to note that two hundred and fifty tons of diamond ore must be mined to obtain a single (1) carat gem quality diamond.  Because of this, a diamond in the (1) carat category (1.00 - 1.49 carats) as a rule, has a higher
value than a diamond in the less than (1) carat class (0.90 - 0.99 carat).

Everything else being the same, the value of a diamond increases very rapidly in relation to carat weight, since larger diamonds are more difficult to find and more desirable as gemstones.

The Four C's: Carat (weight)  |   Clarity  |   Color  |   Cut

| Back to Index |