The term carat dates back all the way to ancient times when gemstones are weighted against a carob bean where one bean equals to one carat. In 1913, the carat system is internationally standardized and adapted to the metric system. One carat now weighs at 200milligrams.

Carat is often confused with size when in fact it is a measure of weight. It should also not be confused with the term Karat which is a measurement of the purity of gold alloys. Points are also oftenly used to describe the weight of smaller diamonds where 1 point is the equivalent of 0.01 carats. One thought to keep in mind is that though size and weight matters, it is not a measurement of your love!

1 ct = 200 milligrams or 0.2 gram

1 ct = 100 points (points often used for smaller diamond)

How big is carat:

Although carat is measure of weight, below is the approximate size of carat.

0.25 ct ~ 4.1 mm

0.5 ct ~5.2 mm

0.75 ct ~5.9 mm

1.0 ct ~6.5 mm

The value of diamond rises exponentially with carat weight because larger diamonds are rarer than smaller diamonds. The size of diamond grows with age, every diamond takes 1 billion – 3 billion years to form. A large diamond with 2 ct is more than double price of two of 1 ct diamond with 50 points for equal quality. Carat is the biggest impact on price.

See also how to budget on diamond carat.