Five points equals .5 carats where one carat equals 1.00 points.
If you mean 1/4 carat, that is one quarter of a carat or 25 points (one carat = 100 points) .
The diamond either weighs 100 points, or a full carat, or it weighs 80 points or 80/100ths of a carat.
'Cents' or points usually describe diamond weight that less than one carat. One carat equals 100 cents or 100 points.
One hundred points are equal to one carat.
As far as gemstones are concerned, carat (karat) is used to measure their weight (as opposed to metals where carat refers to purity). There are 100 points (pts.) to a carat so a 1.0ct diamond is equal to 100 points; a half carat diamond is equal to 50 points and so on.
One hundred points make up one carat -- usually. Specifically, carat indicates the stone's weight; that the weight is described in points is not as precise as describing its weight in carats.
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."
Ninety points means .90 carats, 9/10ths of a carat, 90/100s of a carat.
Forty points is equal to 40/100s or 4/10s of a carat -- almost half a carat.
Points Value = 5 Points Plus Value = 7
One hundred cents make one carat, where cents is an older term for points.
First, understand that if your 'one carat' diamond has '80 points', it may not weigh one carat. Then, take your diamond to a certified gemologist who can tell you 'how much' can be attributed to your diamond.