Each diamond is unique and as such no two are exactly alike. Historically, until the middle of the 20th century, there was no common, universal method for evaluating and classifying diamonds. Nowadays the 4Cs are the method employed to evaluate the quality of any diamond, anywhere in the world.
Explaining the 4Cs is essential, so that our customers will be aware of exactly what they are buying.

The 4Cs: the universally agreed method for grading diamonds


The type of cut depends on the skill of the cutter and affects the quality of the diamond itself. Cutting is an extremely important operation, because it is essential to fully bring out the characteristics of brilliance, scintillation and fire of the diamond. In fact, when a ray of light meets the surface of a diamond, part of it is reflected due to a phenomenon called external refraction. Furthermore, the cut can have a classic round shape or alternative shapes, called “fancy shapes”, such as: heart, oval, marquise, and pear.

The grades for evaluating proportions, symmetry, and polishing are as follows:
Very Good,


The weight of a diamond is measured in carat weight (ct).
1 Carat weighs 1/5 of a gram (1 carat=0.2 grams) and is in turn divided into hundredths, commonly called “points” (1 carat=100 points).
For example, a stone weighing 0.50 ct can also be said to weigh “fifty points” or one weighing 1.09 ct weighs “one carat and nine points”.

  • 1 carat = 100 points = 0.2 grams
  • 0.75 carat = 75 points = 0.15 grams
  • 0.50 carat = 50 points = 0.10 grams
  • 0.25 carat = 25 points = 0.05 grams

The ability to divide a carat into 100 points allows for very precise measurements, down to the hundredth or thousandth of a carat. Logically, the more carats a diamond has, the more the cost increases, not proportionally but exponentially, because the bigger a diamond is the rarer and more desirable it will be.


In diamonds, clarity refers to the absence of inclusions and marks. A diamond’s clarity grade is determined by means of a 10x magnification loupe test to assess these characteristics.
In fact, during its formation a diamond is subjected to extremely high pressures and temperatures. Due to this transformation it is possible for small inclusions and fractures to form which affect its clarity.
For these reasons, an international scale is used to represent the clarity of diamonds. Universally IF represents the best clarity (clarity at 10x magnification) while, on the contrary, an I3 diamond has inclusions visible to the naked eye and for this reason receives the lowest clarity grade. In total there are 9 clarity grades classified as follows.

IF Internally Flawless
VVS1 – VVS2 Very Very Slightly Included
VS1 – VS2 Very Slightly Included
SI1 – SI2 Slightly Included
I1 – I2 – I3 Included

Biloak makes use of ad hoc sales classifications for the selection of our loose diamonds.


Obviously diamonds of different colors are found in nature. For the most part the most popular diamonds are those without color, more commonly referred to as “white diamonds”. In fact, a natural and chemically pure diamond has no hue or color, and consequently will have a higher value. The color of diamonds is graded using the GIA scale, which today serves as the reference scale for the entire world. 

The colors are expressed with a scale that uses the letters of the alphabet, from D to the letter Z. For verification, the diamond is placed under specific lighting and compared against a reference parameter, the Master Stone set of diamonds, which includes a series of stones within the range of the color being examined.

In addition to white diamonds, there are colored stones in different types. In addition to white diamonds or colorless diamonds, Biloak is able to supply black and brown diamonds.

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