This section describes the scientific methods and equipment that is used to evaluate a gemstone and accurately report its value.
Weights & Measures
The weights of diamonds and gemstones is measured in carats, a component of the metric system and their dimensions are described in millimeters. Bracelet and chain lengths are listed in inches.
Grading of color is done with 10x magnification through the pavilion against a white background under a lamp duplicating north daylight. Precisely calibrated color masters are used in grading diamonds to determine the exact color grade (or tone of color) that a diamond exhibits. The grading scale begins with (D) and goes to (Z) with the fancy colors described beyond this point. (D-F) are considered colorless; (G-J), near colorless; (K-M), faint tint; (N-R), very light tint; and (S-Z), light tint. Each progressive letter represents a slightly darker tone but does not identify the hue. Yellow or brown diamonds graded beyond (Z) are classed as one of five levels of fancy color and often have descriptive marketing names such as "cognac" or "coffee." The other colors, such as greens, blues or pinks are designated as fancy color with one of nine tone levels beginning at (K).
© 2013-2017 Van McMinn Jewelry Appraisals