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Explanation of Gem Grading and Appraisal

To establish the relative value of any gem, it is necessary to evaluate its color, clarity, cut, and weight. All terminology used in this appraisal is in accordance with the Gemological Institute of America (GIA). This appraisal contains the following evaluations as defined below:

  1. Shape: Shape refers to the actual shape or outline of the stone (i.e., round or brilliant, pear, emerald, oval, heart, etc.)
  2. Measurements: These are the dimensions of the stone in millimeters. Depth (table to culet) and diameter (across girdle).
  3. Weight: Gems are weighed in units called carats. One carat is equal to one hundred points, or two hundred milligrams. A 1/4 carat stone is therefore 0.25 ct. or 25 points. (See Diamond Weight and Size Chart)
  4. Clarity Grade: If the appraisal is for a diamond, the stone is assigned one of the following clarity grades:

    - VVSI-VVS, - Very, very slightly imperfect. These stones contain very, very small inclusions or surface blemishes which are difficult to locate with lOx magnification.

    - VSI-VS, - Very slightly imperfect. These stones will have internal inclusions or surface blemishes, more numerous and easier to locate than the VVS1 grade under lOx magnification.

    - Sit-SI, - Slightly imperfect. These stones have more serious inclusions and surface blemishes than the VS) -VS, grade. However, these inclusions are not apparent with the naked eye when viewing the stone through the table.

    - I - Imperfect. These stones have more serious inclusions or surface blemishes that can be seen with the unaided eye.

  5. Color Grade:

    - D, E, F - These stones are considered colorless.

    - G, H, I - These stones will face up almost colorless, but will have some slight tint of color. Larger stones will be more tinted than smaller stones.

    - J, K - These stones will have a more tinted appearance than the former grades.

    - L, M, N, 0 - These stones will display a yellowish tint even to the untrained eye.

    - P-X - These stones continue to approach the darker yellow tint.

  6. Depth: Measured in percentage. Ratio of depth to diameter measurements. See diagram.
  7. Table Diameter: Percentage ratio of the table width to the stone diameter. See diagram.
  8. Girdle Thickness: Percentage ratio of the girdle thickness to the total depth. See diagram.
  9. Culet Size: The culet (facet at the bottom tip of the stone) should be as small as possible. Grade is related to size in comparison to the size of the stone.
  10. Finish: This includes other aspects of the stone such as polish, symmetry, and girdle finish.



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