Boston Gem Laboratory
General Information About Your Appraisal:
COLOR:
A grading scale from colorless to light-yellow is used to indicate the color of the diamond with the exception of some fancy colors. The color of a diamond usually refers to the body color which varies from colorless to a very pale yellow, grey, or brown. In most colored stones, color can be described in terms of hue, dominant and additional colors visible; tone, depth or darkness of the color; saturation, amount of hue present. Color is usually the most important evaluation factor for colored stones.
CLARITY:
A grading scale from flawless to imperfect is used to indicate the clarity of a diamond. Clarity characteristics are referred to as inclusions (internal) or blemishes (external). The clarity grade is determinedby the size, number, position color and nature of a diamond's clarity characteristes. The clarity of a colored stone, and its effect on value, depend on the type of gemstone. There are type classifications developed by the Gemological Institute of America to indicate the tolerance allowed in grading based on the growth of gems in nature. Clarity is the second most important evaluation factor for colored stones.
CUT:
The Gemological Institute of America (GIA) Laboratory grades the cut of round diamonds based on computer modeling and observation.
The American Gem Society (AGS) Laboratories grades the cut of round diamonds and fancy shapes based on the components of light performance. (brightness, dispersion, leakage and contrast)
Boston Gem Laboratory (BGL) grades the proportions of round diamonds and fancy shapes based on light performance using GIA and AGS parameters.
COLORED STONE CUT GRADING:
Boston Gem Laboratory (BGL) grades the cut of colored stones based on GIA grading for brilliance, windowing, extinction, symmetry, crown height and pavilion depth, bulge and girdle thickness, table size and finish.
Note: Diamond cut and light return are not always equal. A diamond that is average in cut may exhibit above average light return performance, however, a well-cut diamond maybe average in light return performance.
CARAT WEIGHT:
The metric carat equal 0.200 grams and is the standard unit of weight for diamonds and other gems. Generally, if other factors are equal, the larger the stone, the greater the cost.
"Jewelry is replaced by the description and not by the price on the appraisal."
List of Gemological Instruments
BOSTON GEM LABORATORY ~ rev.21June16
