Diamonds are weighed in a unit of measurement known as carats (ct). The term carat was first used by ancient merchants in the Middle East in approximately 500 B.C who determined the weight of diamonds and other precious stones in correlation to their equal weight in carob seeds. It was thought that the weight of seeds from the pods on carob trees was uniform.
A metric carat equals 0.2 of a gram or 200 milligrams, therefore 5ct is equal to 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.
- 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. Determining factors for the price of a diamond are cut, colour, clarity and carat.
Price per carat x diamond weight (carat) = price of diamond
Round brilliant, ideal cut (perfect proportions), D colour (the best, colourless white), F flawless clarity (the best clarity), 2.5ct in diamond weight.
Price per carat $33,000 x 2.5 carats = $825,00.00 is the price of diamond.
Round brilliant, poor cut (badly proportioned), K colour (faint yellow), I1 imperfect clarity (visible inclusions), 2.5ct in Diamond weight.
Price per carat $2900 x 2.5 carats = $725.00 is the price of diamond.
Diamond Weight Size Scale
(Not actual size)