Diamond Grading Exam Study Materials - Updated for Current Exam

Diamond Grading Exam Study Materials - Updated for Current Exam Abrasion (Abr) - answer - A series of minute nicks along the facet junctions of a fashioned diamond; gives the edges a white or fuzzy appearance. (Assignment 10) Adamantine luster - answer - The highest degree of luster possible in a transparent material. (Assignment 8) Aggregate - answer - A solid mass of individual, randomly oriented crystals, intergrown or held together by a natural binding agent. (Assignment 7) Alluvial deposit - answer - A deposit where gems are eroded from their source rock, then transported away from the source and further concentrated. (Assignment 5) Angle of incidence - answer - The angle at which a ray of light strikes a surface, measured from the normal. (Assignment 8) Angle of reflection - answer - The angle between the normal and a reflected ray of light. (Assignment 8) Annealing - answer - Using heat to stabilize irradiated color in gemstones. (Assignment 12) Appraisal - answer - An estimation of the value of an article, usually for insurance purposes. (Assignment 1) Average girdle diameter - answer - The result achieved by adding the smallest and largest girdle measurements of a round brilliant and dividing by two. (Assignment 14) Bast - answer - Frosted rough diamond. "Bark" in Dutch. (Assignment 9) Bearded Girdle (BG) - answer - Very small feathers that extend from the girdle surface into the stone; can result from the cutting process. (Assignment 10) Belly - answer - The slightly curving center of the long side of a pear, marquise, heart, or oval. (Assignment 16) Beneficiation - answer - A commitment to reserve a portion of the resources derived from any country for the economic development of that country. (Assignment 3) Best Practices Principles (BPP) - answer - De Beers' formalized commitment of itself and its sightholders to the highest ethical standards. (Assignment 3) Blemish - answer - Clarity characteristic that's confined to the surface of a polished gemstone. (Assignment 10) Block caving - answer - Underground mining that involves building a concrete-lined tunnel under an ore deposit, then collecting the ore through openings in the liner. (Assignment 6) Blocking - answer - Placing the first 17 or 18 facets on a diamond. (Assignment 9) Bow-tie - answer - A dark area across the center of an elongated brilliant cut. (Assignment 16) Brick-and-mortar retailer - answer - A traditional store consisting of walls and a fixed location. (Assignment 3) Brightness - answer - The effect of all the diamond's internal and external reflections of white light. (Assignment 8) Brilliant cut - answer - A cutting style in which triangular and kite-shaped facets radiate from a gem's center toward its girdle. (Assignment 16) Brillianteering - answer - Placement and polishing of the star and upper and lower girdle facets. (Assignment 9) Bruise (Br) - answer - A tiny area of impact accompanied by very small, root-like feathers visible at 10X magnification; typically occurs at a facet junction. (Assignment 10) Bruting - answer - Forming the basic face-up outline of a diamond to prepare it for faceting. (Assignment 9) Bulk sampling - answer - Large-scale character sampling. (Assignment 5) Burn Marks (Brn) - answer - Hazy surface areas that result from excessive heat or from uneven polishing caused by structural irregularities; also called polish marks or burned facets. (Assignment 10) Cavity (Cv) - answer - An angular opening created when part of a feather breaks away. (Assignment 10) Central Selling Organisation (CSO) - answer - An agency designed to purchase, sort, evaluate, and sell rough diamonds. (Assignment 2) Character sampling - answer - Testing for the size, shape, clarity, and color of the diamonds in a deposit. (Assignment 5) Characteristic color - answer - The basic color of a fancy-colored diamond. (Assignment 13) Chemical vapor deposition (CVD) - answer - An industrial process adapted to allow growth of