CUT
It refers to the angles and proportions of a diamond.
Based on complex scientific formulas, a very well-shaped diamond will reflect light from one facet to another (like a mirror) and scatter it, reflecting it from the top of the diamond (by the table).
If the diamond is very well carved, then it will have an optimal brilliance, we will talk about diamond fires.
A diamond may also have a size too flat or too thick. In these cases the light will not be reflected optimally and the brilliance of the diamond will be affected.
CARAT
The weight of a diamond is expressed in carat: 1 carat is equivalent to 0.20 grams. A carat can be divided into 100 points. A 0.75 carat diamond is equal to a 75 point diamond and is equal to a 3/4 carat diamond.
The diamond industry uses different types of scales to measure the weight of diamonds. The carat is a measure that is also applied to other precious stones and fine stones.
The carat of the precious stones has nothing to do with the carat of the gold alloys and should not be confused.
CLARITY
Diamonds with few or no inclusions are very rare and therefore cost very expensive. These inclusions may resemble crystals, clouds or tiny threads or tufts. The international standards established that a diamond is considered pure from the moment when the eye of an expert would not discover any defect with a magnifying glass of 10 times (10 times). A scale of purity has been established in order to classify the diamond according to its degree of purity. 
COLOUR
A diamond without color is a colorless diamond.
The diamond industry uses color scales in order to classify diamonds. The color of a diamond has a significant impact on its price.
The color scale extends from D (no color) to Z (light yellow).
The scale starts with D (Diamond), there is no "A", "B" or "C". We advise choosing a diamond whose color is between «D» and «I».
There are also diamonds of all colors: blue, red, pink, green, yellow, black, champagne, cognac, etc ...
Some are very, very rare: red, green, blue, etc …
