The value of diamonds depends on its 4Cs. For the colored diamond, the biggest impact on colored 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:
GIA Colored Diamond Report - This is a complete certificate of colored 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 - The Date the diamond was examined by GIA.
GIA Report Number - Unique GIA report number registered in GIA's extensive global database.
Shape and Cutting Style - The outline of the diamond (shape) and the pattern of the facet arrangement (cutting style) 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".
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 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:
Treated (including: Artificially and HPHT processed treatment).
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).
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) - Any text, symbols, logos, or a unique GIA report number inscribed on the diamond's girdle.
Comments - Includes additional identifying features or characteristics not otherwise represented on the report but that the grader thinks is relevant.
Proportions - The legend does not list all the proportions, only the basic aspect ratio and the kiosk ratio are listed.
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.
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.
Key To Symbols - Lists the characteristics and symbols shown on the plotting diagram, if present
Security Features - Microprinting, security screens, watermarks, a two-dimensional barcode, a hologram, and sheet numbering safeguard report integrity and facilitate document authentication.
QR Code - A two-dimensional barcode that, when scanned, verifies data on the report against the GIA database.