1.5 Carat Round Diamonds

The jump from one carat to one and a half is the first size increase that reads clearly across a room. A 1.50 ct round measures about 7.4 mm against 6.5 mm at a carat: only a millimetre in diameter, but nearly forty percent more surface facing the eye.

Price does not scale with weight, it accelerates. A 1.50 ct round typically costs more than twice a 1.00 ct of matching quality, because larger rough is disproportionately rare. This is the band where dropping one colour grade — G instead of F — buys noticeably more stone for the same money, and where the difference is genuinely hard to see once the diamond is set in white metal.

Clarity deserves slightly more attention than at a carat. The larger table means an SI1 inclusion has more room to show, so check the plot on the report or look at the 360° view before deciding.