Today a carat is equal to exactly 0 2 grams about the weight of a paper clip.
Diamond carat sizes.
Printable carat weight to mm chart.
The surface area is 6 23x6 26mm.
The diamond on the left is 1 00 carat and has a good cut.
Diamonds are sold by the carat shown as ct which is actually a unit of weight though most think of a carat in terms of size.
Likewise the physical size of a 2 carat diamond 8 2mm diameter isn t twice as big as that of a 1 carat diamond 6 5mm diameter.
How large is a half carat diamond.
The word carat comes from the carob seed the original unit of measure for diamond traders.
That is 1 5th of an inch.
Hopefully this clears up the misunderstanding of carat weight and actual sizes.
To compare that a one carat diamond is 6 4mm.
The surface area is 6 23x6 2mm.
So while the one carat is double the weight the face of the half carat diamond is only 21 smaller.
A half carat diamond is usually 5 1mm in diameter.
The diamond on the right weighs in at 0 92 carats and has an excellent cut.
While carat is the standard unit of measurement the millimeter size measurement of a diamond tells you its true physical size.
So even though the two diamonds have different carat sizes they have the same surface area because of the poorer cut of the first one about 10 of the carat weight is wasted.