Diamond Grading Reports
Reputable gemological laboratories, like the GIA Laboratory, are the most consistent and dependable sources of diamond grades. The grades are recorded on diamond grading reports that list the quality factors represented by the Four Cs: Clarity, Color, Cut, Carat weight.
Diamond grading reports, or certificates, date back to the middle of the twentieth century. They’ve become an enormously important part of the modern diamond trade.
Systems at most major gemological laboratories are adapted from the GIA Diamond Grading System because other labs know that the GIA system is universally accepted. Even if a grade is based on the GIA system, however, the only source of an authentic GIA diamond grade is the GIA Laboratory. A quality report from a reputable lab allows a retailer or dealer to choose a diamond without seeing it. A report can also work the other way: You can check a diamond that's accompanied by a quality report to make sure it matches its description. This protects you against switched stones.
The GIA Diamond Grading Report includes an assessment of the 4Cs – Color, Clarity, Cut, and Carat Weight – along with a plotted diagram of its clarity characteristics and a graphic representation of the diamond’s proportions. GIA issues the Diamond Grading Report for loose natural diamonds only, weighing 0.15 carats or more. For standard round brilliant cut diamonds falling in the D-to-Z color range, the report also includes a GIA Cut grade.
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ANATOMY OF A GIA DIAMOND GRADING REPORT |
1. DATE
Date diamond was examined by GIA.
2. REPORT NUMBER
Unique GIA report number registered in GIA’s extensive global database.
3. SHAPE AND CUTTING STYLE
The outline of the diamond (shape) and the pattern of the facet arrangement (cutting style).
4. MEASUREMENTS
Diamond dimensions listed as “minimum diameter – maximum diameter x depth” for round diamonds and “length x width x depth” for fancy-shaped diamonds.
5. CARAT WEIGHT
Weight given in carats, recorded to the nearest hundredth of a carat. One carat is equal to 1/5 of a gram.
6. COLOR GRADE
The absence of color ranging from colorless to light yellow or brown when compared to GIA Master Color Comparison Diamonds. Graded on a D-to-Z scale. If “*” appears next to the color grade, a color treatment was detected.
7. CLARITY GRADE
The relative absence of inclusions and blemishes. Graded on a scale from Flawless to Included based on size, nature, number, position, and relief of characteristics visible under 10x magnification.
8. CUT GRADE
For standard, D-to-Z color, round brilliant diamonds. Cut grade incorporates the aspects of face-up appearance, design, and craftsmanship. Graded on a scale from Excellent to Poor.
9. POLISH
Smoothness of the diamond’s surface, assessed on a scale ranging from Excellent to Poor.
10. SYMMETRY
Exactness of the diamond’s outline, and the shape, placement, and alignment of its facets, assessed on a scale ranging from Excellent to Poor.
11. FLUORESCENCE
Strength and color of the diamond when viewed under long-wave ultraviolet light. A fluorescence description of “none” represents a range of fluorescence from Indiscernible to Very Faint. Used for identification purposes.
12. INSCRIPTION ( S )
Any text, symbols, logos, or a unique GIA report number inscribed on the diamond’s girdle.
1 3 . C O M M E N T S
Additional identifying characteristics or features that are not otherwise represented on the report. If a treatment is detected, such as laser drilling, it would be described here.
14. PROPORTION DIAGRAM
Graphic profile representation of the diamond’s actual proportions.
15. PLOTTED DIAGRAM
Approximates the shape and cutting style of the diamond. Symbols indicate the type or nature, position, and the approximate size of a clarity characteristic.
16. KEY TO SYMBOLS
Lists the characteristics and symbols shown on the plotting diagram, if present.
17. GIA COLOR SCALE
Illustrates the GIA Color grades and their relative positions in the GIA Diamond Color Grading System.
18. GIA CLARITY SCALE
Illustrates the GIA Clarity grades and their relative positions in the GIA Diamond Clarity Grading System.
19. GIA CUT SCALE
Illustrates the GIA Cut grades and their relative position in the GIA Diamond Cut Grading System. Available for standard round brilliant cut diamonds in the D-to-Z color range and Flawless-to-I 3 clarity range.
20. SECURITY FEATURES
Microprinting, security screens, watermarks, a two-dimensional barcode, a hologram, and sheet numbering safeguard report integrity and facilitate document authentication.
21. QR CODE
A two-dimensional barcode that, when scanned, verifies data on the report against the GIA database.
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