Carat Weight

Carat is a weight measurement used exclusively for diamonds and gemstones. Don’t confuse this with Carat or Karat used for gold purity. Prices go up exponentially with carat weight. 100 points = 1 carat. Half a carat = 0.50ct or 50 points, and so on.

Carat Weight

Different shaped diamonds will appear smaller or larger next to each other as some shapes by their nature, hold more weight in their depth. For example, a 1.00ct Cushion Cut Diamond (with a square ratio) averages around 5.4mm - 6.2mm long. In contrast, a 1.00ct Marquise Cut Diamond has an approximate length of between 8.97mm - 12.2mm, which is a dramatic visual difference.

Estimated Diamonds Weight Tables

Carat Weight Information

Diamonds are weighed in a measurement called Carats. The origin of the word and weight unit was first used by ancient merchants in the Middle East in approximately 500 B.C. The unit weight used for diamonds and other precious stones was determined by the equal weight of the carob seed. The weight of a seed from the seed pod of the carob tree or locust bean tree was uniformly equivalent to one carat in weight.

Carob tree and seed pods

A metric carat equals 0.20 of a gram or 200 milligrams, so therefore 5ct equals 1g. This is standard unit of weight used for diamonds and most other gems.

One Metric Carat may be expressed as the following:

  • 1/5 gram
  • 200 milligrams
  • 0.20 gram
  • 100 points


A Metric Carat is broken down into a smaller measurement of weight called "points" There are 100 points of weight in one carat.

Portable diamond scales


  • 100 points equals 1.00 one carat
  • 50 points equals 0.50 of a carat or half a carat
  • 125 points equals 1.25 carats or one and a quarter carats
  • 33 points equals 0.33 of a carat or one third of a carat
  • 75 points equals 0.75 of a carat or three quarters of a carat
  • 87 points equals 0.87 of a carat or expressed as a 87 pointer
  • 29 points equals 0.29 of a carat or expressed as a 29 pointer

Diamonds and other gems are sold by carat weight; the other determining factors for price are the whole combination of Cut, Color, Clarity and Carat weight.

Pricing Examples

Diamond A:

Round Brilliant, Ideal Cut ( Perfect Proportions) D Color (The highest/best, colorless exceptional white) Clarity F Flawless (The best clarity) 2.5 carats in Diamond weight.

Price per carat equals $33000 x 2.50 carats = $82500 is the price of diamond.

Diamond B:

Round Brilliant, Poor Cut (badly proportioned) K color (Faint yellow tinted) Clarity I1 Imperfect (visible inclusions) 2.5 carats in Diamond weight.

Price per carat equals $2900 x 2.50 carats = $7250 is the price of diamond.

Diamond weight size scale

(Not to size)

Diamond weight size scale

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