What are the 4 C's of diamond?

Diamond quality assessment depends on 4 factors based on international standards - Carat, Color, Clarity and Cut. The 4Cs indicate the value of a Diamond have become international principles in buying and selling Diamonds.

• Carat (weight of the diamond) is the first C.
  A carat is a unit of measurement for the weight of a Diamond. 1 carat is equal to 0.2 grams. Carat is called “Tang” in Thai language, therefore 1 carat of Diamond is equal to 100 tang. Carat weight depends on the cut and size of the raw Diamond crystal. The price of the Diamond depends on how difficult it is to find raw crystals (Rough Diamond). The larger the crystals, the rarer to find.This makes large, heavy Diamonds much more expensive than smaller Diamonds. For example, a 2-carat Diamond will be more expensive than two 1-carat Diamonds, even though the overall weight is the same. The price of the Diamonds will not increase proportionally and will be higher based on rarity. Therefore, a 2 carat Diamond is not twice the price of a 1 carat Diamond, or a 1 carat Diamond is not twice the price of a 50 carat Diamond.

• Color (the color of the Diamond) is the second C.
  Most Diamonds seen fall into two groups - the first group are Diamonds that are clear, colorless to light yellow. In evaluating quality, it starts with the letter "D", which is considered the best grade, and moves down to the lowest grade, which is “Z” Color. The second group is Diamonds that are more intensely yellow than Z Color and are classified as a Fancy Colored Diamond (Fancy Diamond). In addition to dark yellow color, Fancy Diamonds also come in many other colors such as Dark Brown, Pink, Red, Orange, Blue, Cyan, or Green, among others. Thai people often call the color of Diamonds "NAM", with the highest Water level being Water 100 or D Color, and moves down to "NAM" 99, 98, 97, ... which is comparable to E Color, F Color, G Color , … in that order.
  

• Clarity (the cleanliness of the Diamond) is the third C.
  The cleanliness of a Diamond is an evaluation of the blemishes or flaws of the Diamond. The blemishes are on the inside, called 'Inclusions', while the blemishes on the outside, are called 'Blemish'. The cleanliness of Diamonds usually does not affect the beauty of the Diamond much.
  Although it can’t be seen with the naked eye, cleanliness is very important. The more blemishes the Diamond has, the higher the level of cleanliness, resulting in a higher price for Diamonds. Level of cleanliness of Diamonds are divided into 6 categories, 11 levels, arranged from most clean to least as follows:
     Flawless (FL)
     Internally Flawless (IF)
     Very Very Slightly Included (VVS1 and VVS2)
     Very Slightly Included (VS1 and VS2)
     Slightly Included (SI1 and SI2)
     Imperfect (I1, I2, and I3)

• Cut (Diamond cutting) is the last C.
  Diamond Cutting considers the following 3 elements: Proportion of a Diamond (Cut Grade), Polish, Symmetry.
  There are 5 grade levels for evaluating all 3 elements: Excellent (Ex), Very Good (VG), Good (G), Fair (F), and Poor (P). Therefore, Diamonds that are perfectly cut in all three aspects, must be graded as Excellent or called Diamond 3EX.