The value of the diamond is mainly comprehensively inspected from the following four aspects: carat, color, clarity and cut. This is what we often say the 4C standard. The price difference is within 3% for diamonds that are equal in quality, color, clarity and cut. And the price difference spreads from 20% and 30% if the diamonds possess the same quality but different grades of colours. For diamonds that are different in cutting, the price difference spreads from 30% to 40%. For diamonds that are different in clarity, the price difference can spread from 40% to 50%. The difference in price of a one carat diamond in best color, clarity and cut and a same sized one with less color, clarity and cut can spread from 70% to 80%.
Now let's learn the 4C standard of a diamond.
The 4C standard: Carat, Cut, Color and Clarity
Carat
It is easy to understand that the price is influenced by diamond weight, for diamonds prices vary from weight to weight. But the relation between price and weight is not a simple positive phase relation. For instance, a four carats diamond’s price is not the sum of 4 one carat diamonds. The price of the four carats diamond is likely to be eight or ten times the price of 1 carat diamond, or even higher.
1 carat equals 0.2 gram, because diamonds are precious and rare, so we need to further subdivide the diamond on the measurement. For example, one carat is then divided into 100 points and a 0.18 carat diamond can be called 18 points.
As a unit of weight, carat originates from the a carob seed living on the edge of Mediterranean in Europe. This plant blooms pink flowers and bears pods with brown nuts of 15 cm in length, which can be used to make glue.The carbo is peculiar that no matter where it grows,each nut of this plant weighs the same. In view of this feature, in the history, this fruit is used as the determination of weight, which gradually become a unit of weight to measure precious and subtle materials. Till 1907, the name “carat” was agreed internationally as the unit of measurement for gems and it is still using today.
The relation between the diamond weight and price can be expressed as follows: diamond prices equals the square of its weight multiply base price and K. At present, diamond in the market can be classified into four categories by weight: above 1 carat can be view as big ones; 25 points (0.25 carats, namely 1 carat is divided into 100 points) to 1 carat are considered as medium ones; diamonds those are less than 25 points are regarded as small ones; 1 out of 4 points is also known as cents ones.
There is a relatively fixed corresponding relationship between size and weight because the cut is standardized. To take round diamond as an example, a 1 carat diamond’s waist is 6.2-6.6 mm in diameter, a 0.5 carat is 5.15 mm in diameter and 0.25 carat is about 4.1 mm (girdle will influence this correspondence, of course).
Precious diamonds can be classified in the following way by colours:
1. Water diamond: A kind of transparent colorless diamond which is as pure as water, especially the ones with light blue inside are considered as the best. For example, the super diamonds around the world such as “Jonker”, etc.
2. Red diamond: a transparent pink or cardinal red diamonds, in which the "pigeon blood red" ones are especially rare. For example, notable diamonds such as "Russian red" etc. These diamonds are mainly produced in Australia.
3. Blue diamond: a sky blue, blue and dark blue transparent diamond, among which dark blue is the best. This diamond is different from all the other colors of diamonds for it can be used as semiconductor. It is considered as a rarity because it is very uncommon. Representatives are notable diamonds such as "hope", etc. South Africa's Pu Meier mine is the main producing area.
4. Green diamond: a pale green or green transparent diamond, among which the emerald green is the best. The famous “The Dresden Green” is a representative. Zimbabwe (Rhodesia) is the main producing area.
5. Purple diamond: a pale purple or purple transparent diamond, among which vivid purple is the rarity. The former Soviet Union is the main producing area.
6. The gold diamond: a golden transparent diamond which is the common type among colored diamonds.
7. Black diamonds: black diamond is not usually considered as a diamond, but big black transparent ones can also be regarded as precious diamond, such as "the Star of Africa".
Clarity
Diamonds are often thought to be glittering and translucent, but in fact most of the diamonds contain tiny inclusions. This is the result of environment changes in the process of developing and crystallizing and the invasions of other crystals. Generally speaking, natural diamonds contain contents and diamond clarity refers to the number, location and size of inclusions within natural diamonds. Being the brightest and most dazzling, completely pure diamond is the most expensive diamond with the highest index of refraction. The fewer are the inclusions and the less obvious are the inclusions, the higher is the value of a diamond.
Although most of the diamonds contain inclusions, but the beauty of the diamond itself they will not be influenced. Of course, fewer and smaller inclusions have less impact on the light penetrating inside the diamond, thus making the sparkle of diamonds more beautiful.
FL, IF, VVS, VS, SI and I：
Diamond clarity is generally classified into 6 grades:
Here is a diagram showing diamond clarity grades. The diamond hierarchy above is formulated by the world's most authoritative diamond appraisal agencies - the American College of Gem (GIA)
Flawless, F or FL for short, refers to diamonds that are perfect inside and outside without any defects. Some with small problems can also be included in the FL level. In this level, extra small facet are allowed on the pavilion, but little facet is invisible from the table; the natural native small crystal or cleavage plane is visible with its size less than the width of the waist, or if it makes the waist round; There are very small dots inside the diamond which is colourless without affecting the perspective.
Internally Flawless, IF for short, refers to diamonds that are perfect inside and there is little flaw on the surface, with very very slight included flaw or very little flaw that can only be observed from the pavilion. The difference between VVS1orVVS2 is that VVS2 has extremely small continous dots and stubbles in it（generally no internal defects）
Very slightly included, VS1 or VS2 for short, refer to diamonds with very small defects and the size and location of these defects can also be observed. The difference between VS1 and VS2 is that VS2 may have small cotton materials and wool stubbles inside.
Inperfect, I1、I2、I3 for short, refer to diamonds with obvious flaw and sometimes the cleavage plane can also be observed.
Suggestions on diamond clarity:
(1) The higher the clarity of diamond is, the higher the price. When you want to buy diamonds of high clarity or for investing and collecting, then VS level or above is the most appropriate one for you. If you have no special requirements, SI level has the highest cost-performance because naked eyes are unable to distinguish between SI and VS levels. Besides, defects are also part of the diamond, which is the unique natural mark on each diamond.
(2) You do not necessarily have to buy diamonds of VS、I level. For diamonds embedded in the platinum, K level color would be good enough. And for diamond jewelries under 0.25 ct, especially bracelets, earrings, pendant, etc, there is no need to be demanding on the color and clarity. As long as the workmanship is good and the "fire" (refers to the dispersion of light by diamond) appears, then the jewelries are considered as good ones .