The other diamonds lose that sparkle through their undersides. Well, well, that is why many jewelry stores use what are called diamond lights. They are of such high intensity and particular wavelength that the lack of diamond sparkle under ordinary light is overcome. More details about CUT . It takes 100 points to equal 1 ct.
All fractions have a range of points that they can be.
A diamond's weight is measured to the third decimal place, a thousandth of a carat, and rounded off to the nearest hundredth. Of course, the larger the diamond, the rarer it is, and the more expensive per carat it will be.