This article is part of HHGR's continuing education series for our valued customers.
Professional gemstone grading is performed by trained specialists known as Graduate Gemologists, who are educated in the scientific identification, evaluation, and documentation of gemstones. While both diamonds and colored gemstones undergo careful examination, the grading systems and evaluation priorities differ significantly between the two.
Diamond Grading
Diamonds are graded using a standardized system commonly known as the Four Cs: Carat weight, Color, Clarity, and Cut. This system provides a consistent way to evaluate diamonds and communicate their quality within the jewelry industry.
Graduate gemologists examine diamonds using specialized instruments designed to reveal subtle characteristics:
| Gemological Microscope – Used to examine inclusions and surface features that determine a diamond’s clarity grade. Magnification allows the gemologist to map internal characteristics that help identify the stone and confirm natural origin. | |
| 10x Loupe – A small handheld magnifier considered the standard for clarity grading in the diamond industry. Clarity grades are typically determined at 10× magnification. | |
| Master Color Comparison Stones – A controlled set of diamonds with known color grades used as references when determining where a diamond falls on the color scale, typically ranging from D (colorless) to Z (light yellow or brown). | |
| Precision Carat Scale – Measures the weight of the diamond to a high level of accuracy, as even small differences in carat weight can significantly affect value. | |
| Proportion Measuring Tools – Devices such as digital calipers or proportion scopes are used to measure the diamond’s dimensions and evaluate the quality of its cut. |
These measurements are combined to produce a grading report that objectively describes the diamond’s characteristics.