The Grading Process
Natural diamond grading at Naturalmark Lab Pvt. Ltd. follows a systematic process based on the 4Cs (Carat, Cut, Color, and Clarity), along with additional evaluations for authenticity and other characteristics. Here’s a step-by-step breakdown:
Pre-Grading Examination
Cleaning the Diamond: The diamond is cleaned to remove any dust, oil, or residue that may affect grading.
Initial Inspection: The diamond is examined under magnification to check for surface features, inclusions, and fluorescence.
Identification: Screening machine & Advanced instruments (e.g., spectrometers, microscopes) are used to confirm whether the diamond is natural, natural treated ( HPHT ), Labgrown or synthetic.
Carat Weight Measurement :
The diamond is weighed using a precise electronic balance.
Color Grading
The diamond is compared to master stones under controlled lighting. Color is graded on a scale from D (colorless) to Z (light yellow or brown). Fluorescence is also checked under UV light.
Clarity Grading
The diamond is examined under a 10x magnification microscope. Inclusions (internal) and blemishes (external) are identified and mapped. Clarity is graded from FL (Flawless) to I3 (Included).
1. FL (Flawless): No inclusions or blemishes under 10x magnification.
2. IF (Internally Flawless): No internal flaws; only minor surface blemishes under 10x magnification.
3. VVS1/VVS2 (Very Very Slightly Included): Minute inclusions that are extremely difficult to see under 10x magnification.
4. VS1/VS2 (Very Slightly Included): Minor inclusions that are somewhat easy to see under 10x magnification.
5. SI1/SI2 (Slightly Included): Noticeable inclusions under 10x magnification but not easily visible to the naked eye.
6. I1/I2/I3 (Included): Obvious inclusions under 10x magnification, often visible to the naked eye, and may affect durability.
Cut Grading
The proportions, symmetry, and polish of the diamond are analyzed. Parameters such as table percentage, crown angle, pavilion depth, and girdle thickness are measured. The overall cut grade (from Excellent to Poor) is determined based on light performance.
Additional Tests
Fluorescence Analysis: Determines if the diamond emits light under UV exposure.
Optical Properties: Checked using spectrometers to confirm natural origin.
Inclusion Plotting: A clarity diagram is created for documentation.
Report Generation
The final grading report includes details on 4Cs, fluorescence, symmetry, polish, proportions, and a clarity plot. The diamond may also receive a laser inscription on the girdle for identification.
Quality Assurance & Final Verification
A senior gemologist cross-checks the grading to ensure accuracy and consistency. The diamond is securely packaged, and the grading report is issued to the client. This systematic process ensures accurate and reliable grading of natural diamonds in a Naturalmark Lab.
The Naturalmark diamond grading report covers following aspects of grading.
How to read a Diamond Grading Report -
Report : It carries a unique report number, an alpha numeric value for that loose diamond graded at Naturalmark Lab and is also used by the customer to check its authenticity by putting in the verify report section of our website.
Description : This tells whether the stones are of Natural or synthetic origin, treated or non-treated and the type of treatment, if any (HPHT etc.)
Remarks : Any additional information required will be mentioned in the remarks section.
Shape : It gives details about the shape of the diamond graded.
Dia pcs/Wt : It tells the number of loose diamonds in a packet and the total carat weight of loose diamonds.
Color : The color grade in diamond is denoted by Alphabets from D- M , depicting colourless or pure, white to slight yellow and extending till Z and Z+ covering fancy color diamonds. Naturalmark uses a self designed clock to show the color gradation in a diamond. This beautiful clock can be purchased , and can easily explain a laymen about the various colors in which a diamond can be available.
Clarity : Loose diamonds are being graded from FL to I3 clarity.
Dimensions : It indicates diameter (twice) and height in mm. The image of the diamond is shown in the report.
