Diamonds - Carat Weight
A diamond's weight is expressed in carats; one carat is subdivided into 100 points. A jeweler must weigh the diamond before and after showing it to the consumer. It is a big mistake to buy a diamond on the basis of weight alone. Many retailers sell 45-point diamond and exhibit them as "approximately" 1/2-carat.
There is nothing wrong with buying a "light" 1/2-carat., or "light" 1-carat. diamond; however, their value is significantly less than a full 1/2- carat or 1-carat diamond.
Also, many folks end up buying diamonds between 0.90 carat thru 0.99 carat as one carat. However, the price difference between identically graded 0.99 carat and 1.00 carat could be 30% to 60% depending upon the quality.