The Weight of a Diamond: Carat

1 carat = 0.20 grams. 
You might also hear about "points": 1 carat is divided into 100 points: so, a diamond that weighs 0.25 carats is equal to 25 points or even 1/4 of a carat.

The Measurement of a Diamond's Weight 

A diamond is weighed to the nearest hundred and strict rules have been established regarding the rounding up. In fact, one can only round the weight up to the higher value if the thousandth digit is a 9 (instead of a 5). Thus, a ring with a diamond weighing 0,999 carat is a diamond of 1,00 carat while a diamond of 0,998 carat is a diamond of 0,99 carat. 
This weight is determined very precisely, usually with the help of an electronic scale. 

The Price of a Diamond According to its Weight 

The price of diamond is not just proportional to its weight, but the bigger a diamond is, the rarer it is, and thus it is more expensive. As such, the value of a diamond of 2 carats is not twice that of a 1 carat diamond but much more than that. 
On our site, you will find jewellery for all budgets and occasions: wedding rings, engagement rings, necklaces, bracelets, earrings, etc.

The dimension of a diamond in relation to its weight

Please find below an indication of the average width of a diamond in relation to its weight:

- 0,05 carat : 2.5 mm
- 0,10 carat : 3 mm
- 0,20 carat : 3.8 mm
- 0,30 carat : 4.5 mm
- 0,40 carat : 4.8 mm
- 0,50 carat : 5.2 mm
- 0,70 carat : 5.8 mm
- 1 carat : 6.5 mm
- 1,50 carat : 7.4 mm
- 2 carat : 8.2 mm
- 3 carat : 9.4 mm

The Origin of the Word "Carat"

Why the "carat"? It comes from the name of a tree, the carob, whose seeds weigh about 0.2g each and were formerly used as a unit of measurement. 

But be careful, you should never confuse the carat, which is the unit of measurement of diamond, with the carat of gold which is not an expression of its weight but of its purity, that is to say, the gold portion of your jewellery. Thus, 18 carat gold jewellery means that for 24g of alloy you have 18g of pure gold.