It is important to possess an accurate understanding of dealer jargon or trade language concerning weight so misunderstandings are avoided. The following will be commonly used terms in the trade.

Carat weight can be expressed in points instead of carats, or as a combination of both. For example, a 1.47 carat could be expressed as: “one forty seven” ; “one point forty seven”; “a carat forty seven”; “one point four seven carats”; a hundred forty seven points”; “a carat and forty seven points”. The most common useage among dealers is the first example, “one forty seven”. A .58 carat would commonly be called a “fifty eight” or a “fifty eight pointer”. It is common for anything under a carat to add “pointer” at the end. Uncommon would be the example “a hundred forty seven points” or “a carat and forty seven points”. Many times a dealer can tell how inexperienced you are or how long you’ve been in the business by the terms that you use. You’ll quickly become accustomed to these terms as you deal with more and more people in the trade.

Small diamonds, called melee (rhymes with “jelly”), don’t see the substantial price increases as weight increases as compared to larger stones since they are very much more common. Melee would include any diamond that weighs less than 0.18 carat. Most dealers consider 0.18 the beginning of the 1/5 carat category
Grainers

Many dealers use the term grainer. A grainer represents a 1/4 ct.

One Grainer = 1/4
Two Grainer = 1/2 ct.
Three Grainer = 3U4 ct.
Four Grainer = 1.00 ct.
Five Grainer = 1.25 ct.
Six Grainer = 1.50 ct.
Seven Grainer = 1.75 ct.
Eight Grainer = 2.00 ct.
Etc.
General Weight Categories:

0.01-0.03 – melee

0.04-0.07 – melee

0.08-0.14 – melee

0.15-0.17 – melee

0.18-0.22 – 1/5

0.23-0.29 – 1/4

0.30-0.37 – 1/3

0.38-0.45 – 3/8

0.46-0.49 – Light 1/2

0.50-0.69 – 1/2: This is where a weight increase within a weight category will affect price more readily.

0.70-0.89 – 3/4: Again, the PPC on an 0.88 is going to be perhaps 10 to 15% higher than a 0.70 ct.

0.90-0.99 – Light carat: Since there is a smaller weight variance in this narrow category the difference between a 0.90 and 0.99 carat may only be 5 to 7%.

1.00-1.49 – One carat: This of course would be a very loose definition of a size category since there are perhaps three categories within one. 1.00+ ct.; 1.25+ ct.; 1.40+ ct. The price increases as you move closer to the 1.49 mark and will be quite obvious at that point. Again, the 1.40-1.49 ct. diamonds are going to be much more difficult to find and therefore demand a much higher price per carat than the more common 1.00 carat sizes.

1.50-1.99 – 1 1/2 carat: Usually a jump in price starts at 1.70 and again at 1.90 ct. A 1.97- 1.99 ct. will likely be priced close to the 2.00 ct. price.

2.00-2.99 – Two carat plus: The same rules will apply for this size category and larger. Watch for price increases in 2.40+, 2.70+ and 2.90+, and again 2.97-2.99 will be very similar in price to 3.00 ct.

Note: Proportions will always have a direct influence on the value of the finished diamond. Example: A fine make that weighs 1.98 carats, could easily be valued higher than an inferior make of the same grade, that weighs 2.00 carats.