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About GIA

GIA is the world’s foremost authority on Jewelry

The 4C are as such: Color, Clarity, Cut, Carat . All 4, starting with the letter C, are the criterion used to determine the method for establishing the quality of all Diamonds in the world.

To allow customers to have a sense of security and ease of mind while purchasing Diamonds, GIA created the standard of "4Cs". Knowing the “4C” of a Diamond, customers can determine a Diamond quality easily, understanding what they are purchasing exactly.

Understanding the 4Cs of Diamond

Color

GIA’s Color-Grading Scale for diamonds has been used as an industry standard. The scale begins with the letter D, representing colorless, and continues with increasing presence of color to the letter Z, which is light yellow or brown. Each letter grade has a defined range of color appearance. Diamonds are color-graded by comparing them to stones of known colors under controlled lighting and precise viewing conditions.

Many of these color distinctions are so subtle that it will appear invisible to the untrained eye. But these slight differences makes a very big difference in Diamond Quality and Price.

Clarity

Natural Diamonds are formed under extreme high temperatures as well as pressure deep within the earth. This results in a variety of internal characteristics called Inclusions and external characteristics called blemishes.

A Diamond of Clarity“VS1” and “SI2” may look the same in untrained eyes.
Clarity is Graded under standard viewing conditions with 10x magnification.

FLAWLESS (FL)
No inclusions or blemishes are visible to a skilled grader using 10× magnification

INTERNALLY FLAWLESS (IF)
No inclusions and only blemishes are visible to a skilled grader using 10× magnification

VERY, VERY SLIGHTLY INCLUDED (VVS1、VVS2)
Inclusions are present but hardly visible to a skilled grader using 10× magnification

VERY SLIGHTLY INCLUDED (VS1, VS2)
Inclusions are present and range from hardly visible - visible to a skilled grader using 10x magnification

SLIGHTLY INCLUDED (SI1, SI2)
Inclusions are present and very noticeable to a skilled grader using 10x magnification

INCLUDED (I1, I2, I3)
Inclusions are present and very obvious to a skilled grader using 10× magnification and may affect transparency and brilliance

During a Diamond’s natural formation, virtually all Diamonds contains small imperfections. Flawless {FL} refers to Diamonds that are completely without such imperfections.

Cut

Diamonds are reowned for its ability to transmit light and intense sparkle.

Beauty and Value of a Diamond is highly dependent on its Cutting. It is said that a Diamond’s Cut is the most complicated and toughest part in judging a Diamond’s 4C.

For Round Brilliant Cuts, GIA grades Diamonds based on these 3 optical features:

• Brightness : Amount of Internal and External white light reflected.
• Fire : Scattering of white light into colors of the rainbow.
• Scintillation : Amount and Intensity of sparkles a Diamond can produce.

A Diamond’s Cut Grade is further sub-divided into 3 categories, where the design and craftsmanship is taken into account.

• Cut : The Diamond’s weight relative to its diameter, and its girdle thickness, which affects its durability.
• Symmetry : The symmetry of its facet arrangement.
• Polish : The quality of polish on the Diamond’s facets.

In a Perfect Cut Diamond, 8 distinct arrows can be seen when looked though the loupe from a top down view, and 8 hearts from a bottom up view.

Carat

Measurements of a Diamond’s Carat is based on its weight. A metric Carat is defined as 200 milligrams (0.2 grams).

Each carat can be subdivided into 100 point, which allows very precise measurements.
For Diamonds below 1 Carat, a jeweller may describe its weight by 'points' alone. For example, the jeweller may refer to a Diamond that weighs 0.25 Carats as a ‘twenty-five pointer.'
Diamonds above 1 Carat are expressed in carats and decimals. For example, the jeweller may refer to a Diamond that weighs 1.08 Carat as ‘one point oh eight carats’.

With the condition of all else being equal, a Diamond’s price increases in accordance to its Carat, because larger Diamonds are much rarer and therefore more desirable. However, 2 Diamonds of equal Carat can have very different values (and prices) depending on 3 other factors of the Diamond’s 4C.

Advanced Diamond knowledge

Information on Fluorescence

In Diamonds, Fluorescence is the effect that ultraviolet (UV) light has on a diamond. When you stand under a blue light or ultraviolet light, you may see that your whites gets brighter or your teeth appears to glow. This is the same effect Diamonds have under the UV rays. Fluorescence is the visible light that a Diamond emits when it is exposed to UV rays. On a GIA Diamond Grading Report, Fluorescence refers to the strength, or intensity, of the Diamond’s reaction to long-wave UV light, which is an essential component of daylight.

Treated Diamonds, Artificial Diamonds, Simulated Diamonds

In recent years, there has been an increase in demand for Treated Diamonds, Artificial Diamonds, as well as Simulated Diamonds. As a result, scientific advancement for such Diamonds have improved by leaps and bounds, making it far more difficult to distinguish these from a completely natural Diamond that has not gone through processing.

Treated Diamonds

Also known as Enhanced Diamonds, these refer to natural Diamonds that have gone through specific treatments, which are designed to improve the visual characteristics of a Diamond. Treatments for Diamonds are generally categorized into 2 different types, either for improving its Color or for Clarity. GIA only certifies Diamonds that have undergone permanent treatments, which will be indicated on the report.

1) Color Treatments

There are 3 major methods used to artificially alter the Color of a Diamond.
Irradiation: By exposing a Diamond to radiation, the atomic structure of a Diamond can be altered to lessen or intensify its Color. This process is usually permanent, and applied to Diamonds which are already Cut and Polished.
Coatings: Applications of thin films or coating on to the Pavilion or Girdle of a Diamond. This thin film or coating are removable, therefore the Color may wear off after some time. This treatment is applied to Diamonds which are already Cut and Polished.
HPHT: Application of High Pressure and High Temperature to Diamonds that are not fully crystallized, also known as ‘Premature Diamonds’. Only Diamonds with high Clarity may undergo this treatment, as inclusions present in Diamonds may cause it to crack when subjected to HPHT. Through this process, Diamonds can have a permanent and drastic difference in Color.

2) Clarity Treatments

There are mainly 2 types of techniques for improving the Clarity of a Diamond.
Laser Drilling: By boring holes in the Diamond using laser, this technique allows removal of dark inclusions. Bleaching agents may then be introduced to improve the inclusions appearance. This process is permanent, however do take note that if a Diamond contains too many drilled channels, it may affect the Diamond’s structural integrity.
Fracture Filling: This is a process where cavities or tunnels left by Laser Drilling is filled with a crystal substance, making the cavities or tunnels look less visible. This process is not permanent, and if subjected to heat or ultra-sonic cleaning, the crystal substance may be destroyed.

Artificial Diamonds

Artificial Diamonds, also known as Synthetic Diamonds are man-made. They are produced in an artificial process instead of geological process. Artificial Diamonds may also be called as HPHT Diamond, or CVD Diamond, named after the 2 common production methods. Artificial Diamonds are identical to natural Diamonds in term of Chemical Composition, Physical Properties as well as Crystal Structure. It is highly difficult for an experienced Gemologist to differentiate between the 2 without the aid of equipment. The value of Artificial Diamonds are lower than natural Diamonds, however it is not highly popular due to the unromantic notion that it is created in a few days, compared to natural Diamonds which takes millions of years to form.

Simulated Diamonds

Simulated Diamonds, also known as Imitation Diamonds, are different from Diamonds in terms of Chemical Composition and Physical Properties. They are however similar in terms of Gemology Characteristics. The most common simulants used are Cubic Zirconia, Moissanite and Quartz. On the Mohs’ (Hardness) Scale, Diamonds are rated as 10. Simulated Diamonds may have a rating ranging 7-9.25 on Mohs’ Scale. Gemological Institutes does not issue Grading Reports for Simulated Diamonds.