De Beers' "Diamonds last forever, one will last forever" regards diamonds as the supreme token of lovers' faithful love, symbolizing loyalty and eternity.

1 points =.1 carat, 2 points =.2 carat, 3 points =.3 carat, 9 points =.9 carat, and 1 points =1 carat =.2 gram.

carat (ct), divided into (pt), the internationally accepted unit of gem weight.

for reference.