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Understanding Color Diamond Certificate

The value of diamonds depends on its 4C element; they are weight, color, clarity and cut. For the color diamond, the biggest impact on color diamond’s price is “COLOR”. As the value of natural diamond is expensive, so generally have an identification certificate issued by professional accreditation institution.

At present, GIA is the leading certification and authentication authority, its rating system and diamond identification certificate providing an accurate and objective basis for consumers who are going to buy diamonds. The following is a sample of GIA certificate; we explain in detail the contents of the GIA certificate:

The GIA certificate is divided into the following sections:

Part 1: General Information

GIA COLORED DIAMOND REPORT: which is a complete certificate of color diamond identification. There is also a COLORED DIAMOND IDENTIFICATION AND ORIGIN REPORT, which is a simplified certificate that includes shape, size, weight, origin and color assessment.

Certificate Issued Date: this refers to the date when the report was printed not when the stone was graded.

GIA Report Number – the vertically displayed number on the left-hand side of the document is the unique diamond identification number: GIAXXXXXX

Shape and Cutting Style: the shape of a diamond describes the outline of its girdle, and includes: Round, Oval, Radiant, Asscher, Marquise, Princess, Emerald, Pear, Heart, and Cushion.

Measurements: dimensions, in millimeters, of the diamond rounded to the nearest hundredth. For a round cut stone, the measurement is “minimum diameter – maximum diameter x depth (culet to table).” For fancy-shaped diamonds, the measurement is “length x width x depth.

Part II: Grading Results

Carat Weight: diamonds are weighed in carats. A diamond’s carat weight is measured to the nearest 1/1000 of a carat but rounded to the nearest 1/100 of a carat.  A carat equals 1/5 of a gram.

Color Grade: one of the more complex categorizations for color diamonds, color grade is a combination of hue, saturation and tone. Hue refers to the color, saturation to the intensity of the color, and tone to the shade.

Color Origin: states the source of color, GIA mainly has 3 descriptions for source of color as below:

  1. Natural
  2. Treated (including: Artificially and HPHT processed treatment)
  3. Undetermined (cannot determine the source of color)

Color Distribution: it refers to the evenness of distribution of color throughout the diamond when viewed face-up using standard viewing procedures. The greater the distribution, the better. Distribution is categorized as “Even” – symmetrical in over 50% of the stone, “Uneven” – asymmetrical in over 50% of the stone, or “Not Applicable” for the grades faint, very light, and light.

Clarity Grade: this assesses the relative absence of inclusions (internal characteristics) and blemishes (external characteristics) of a diamond. There are 11 clarity grades on a scale from the highest grade of Flawless (FL) to the lowest grade of Included (I – graded on a scale of 1-3, with I3 being the lowest).

Part III: Cut and others

Polish: this is the overall condition or smoothness of the diamond’s surface

Symmetry: this is the proportion of the diamond’s outline as determined by the shape, placement, and facet alignment. Two types of symmetry are considered – proportion symmetry and facet symmetry.

Fluorescence: this measure is deemed to be of little value when assessing the value of a colored diamond and used mainly for identification purposes. Fluorescence measures the strength and color of a diamond when viewed under short or long-wave ultraviolet light.

Inscription (s): Laser print of Diamond

Comments:  include additional identifying features or characteristics not otherwise represented on the report but that the grader thinks is relevant.

Part IV: Proportion

The legend does not list all the proportions, only the basic aspect ratio and the kiosk ratio are listed.

Part V: GIA Clarity Scale & GIA Colored Diamond Scale
  • GIA Clarity Scale – it displays the GIA Clarity grades and their relative positions in the GIA Diamond Grading System. The diamond grading scale is divided into six categories and eleven grades.
  • GIA Colored Diamond Scale– it displays the general interrelation of GIA fancy-grade terms, used to describe the combined effect of tone and saturation, in color space.
Part VI: Display Sketch of Clarity Features

The main difference between GIA’s color diamond certificate and white diamond certificate is the color grading, the natural color of the color diamond is much more complex than the white diamonds.


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Asia Fancy Color Diamond Association (“AFCDIA”) is trade promotion organization headquartered in Hong Kong with the primary objective to promote the development of the color diamond industry in Asia, with particular emphasis on the Greater China markets. READ MORE