When the diamond arrives at the GIA, it is assigned a unique tracking number, which identifies the diamond as it goes through the grading process. The submitted diamond remains anonymous and may not include any company names, initials, logos or other personnel to identify the owner during the grading process. This allows GIA to avoid the appearance of favouritism and ensures objectivity.
As the diamond goes through the grading process, it is monitored by a tracking department using electronic surveillance equipment which can pinpoint the diamond’s exact location at any given time. After the diamond has completed each grading step, it is returned to the inventory control department before being sent to the next step, to ensure the distribution of diamonds to graders is completely random.
Step 1: Carat weight and proportions
The first step in the GIA grading process is for the diamond to be weighed and measured. An optical scanning device determines the diamond’s precise measurements, proportions and facet angles, while an electronic micro-balance weighs the carat weight.
Learn more about the carat weight of a diamond.
Step 2: Clarity and finish
The diamond’s clarity and finish are graded under magnification and multiple graders. Graders examine the diamond for any clarity and finish characteristics, any treatments such as fracture filling or laser drilling, and to verify weight and measurement data captured in the Step 1.
The grader states the diamond’s clarity, polish and symmetry. A diamond plot is created, which maps the diamond’s interior and exterior flaws. The grader indicates the size, position and nature of each clarity characteristic. The diamond’s cutlet size and girdle thickness is assessed.
A second grader takes the diamond through the same process and submits a second independent opinion of the diamond. A senior gemologist may also review the grading information and give a third opinion, depending on the diamond’s carat weight, quality and agreement between the two graders. Once agreement is reached, the grading results are finalised.
Learn more about the clarity of a diamond.
Step 3: Colour and Fluorescence
The diamond’s colour is compared to a set of master diamonds – a row of stones laid out from D to Z, representing the standard for each colour grade. Each diamond in the master set represents the least amount of colour in its range. The grader moves the diamond step by step down the line of master diamonds until the grader is able to determine where the submitted diamond falls in the colour grade spectrum. The grading environment is a neutral grey and white, since light source and background can have a significant impact on the appearance of colour within a diamond.
The grader then places the diamond under special UV lighting to determine if the diamond exhibits fluorescence and to what degree. Several graders go through the same process to ensure the accurate colour and fluorescence grades are assigned to the diamond.
Learn more about the colour of a diamond.
Step 4: Cut
The diamond’s brightness, fire and scintillation are assessed and incorporated into the cut grade. The diamond’s measurements, proportions, facet angles, polish and symmetry are also factored into the final cut grade.
Learn more about the cut of a diamond.
Step 5: Laser Inscription
Every diamond is laser inscribed with the GIA report number, which is noted on the diamond grading report / dossier.This serves two purposes, first to track the diamond back to the owner should it lost / misplaced, and second, serves as proof of the diamond's identity linking it back to the diamond report.
Once the grading process is complete, GIA issues the diamond’s report, which is a printed document with micro print lines, a hologram, and other security components. It is then laminated to prevent tampering and to preserve the report over time. It is then placed in a protective sleeve and delivered to the owner or company who submitted the diamond.
Diamonds 27 believes in providing the clients with the best quality diamonds and ensures that the store has GIA graded diamonds for sale.