A round brilliant cut gem of that weight measures in the 6.5mm range at the girdle.
A half carat diamond of this cut measures 5.2 mm at the girdle; a .65 carat diamond measures 5.6 mm at the girdle. A certified gemologist can give you the exact carat weight of your diamond.
At the girdle, this stone would measure about 6.5 mm.
It depends on the shape. For e.g. a 1 carat round brilliant diamond has a width of 6,5 mm. Other shapes, such as a marquise diamond is cut to be a longer shape. A one carat marquise diamond would be about 10 mm x 4,75 mm. Oval, pear and emerald along with the marquise shape visually appear larger than the round and square shapes.
1 carat = 6.5 mm
A 1.75 carat diamond billiant cut is about 7.8 mm and a 2.00 carat stone is about 8.2 mm at the girdle. In order to know the exact carat weight of a stone, one must take it to a certified gemologist and ask that it be removed from its setting and weighed.
A 1.00 carat round brilliant, when properly cut, should measure approximately 6.5 mm in diameter.
A four-carat round cut diamond measures about 10mm at the girdle. Different cuts would have various mm measurements for each weight.
If the diamond is a round brilliant cut, the 3mm measurement at the girdle indicates that the diamond weighs about 1/10th of a carat, or .10 carats.
A two carat round brilliant cut stone will measure about 8.2 mm. A different cut will have a different measurement.
If the diamond is a round cut, the measurement would be 7.4 mm at the girdle. If the diamond is of another cut, the measurement would be different.
Usually, a brilliant cut diamond that weighs one carat measures about 6.5 mm at the girdle.
The diamond weighs .125 carats. Its mm measurements depend on the cut.