In terms of a round brilliant diamond, a properly cut stone should measure approximately 5.2 mm in diameter.
One carat weight of diamond weighs .20 grammes, so your diamond is about half that weight, or roughly half a carat.
A forty-point diamond is nearly half a carat, which would be fifty points.
A one-half carat diamond weighs 100 milligrams = 0.10 gram.
Generally, you would write .50 carat to represent a half-carat stone.
Half carat is the term used to measure the weight of the real diamond. A diamond's weight does not define or detract from the fact that the diamond is or is not a real diamond.
The total weight of all the diamonds combined in the carat total weight equals one half carat -- .50. The mm measurement of each individual diamond does not depend on the total carat weight of the collection.
A 60-point diamond weighs just over half a carat (.50 carats). The size of the ring is not related to the weight of the diamond.
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.
A carat is a measurement of diamond weight. From Amazon.com: "Carat is the unit of measurement used to describe the weight of diamonds. One carat is equal to 0.2 grams, or 0.007 ounces (avoirdupois). Five carats equals 1 gram, and 141.7 carats equals 1 ounce."
A 1.00 point diamond is one carat, so a .12 point diamond is a little over 1/10th of a carat.
A one carat diamond in the round brilliant shape measures aproximately 6.5mm at the girdle. If the diamond is another cut, measurements will be different.
1 carat is 0.2g, so 1/2 of a carat equates to a 0.1g gemstone.