Which unit is used for measuring gemstones and pearls?

I knew carat was gem weight but didn't know (or ever think about) equivalency to 200mg. e.g. a 2.5 carat diamond weighing ½ gram

How beautiful is that rock.

Qu al ahaooaoa tam

I love diamond

Imagine looking at a beautiful 2.5 carat diamond ring on my (Kim Suzette Young) finger !!!