DIAMOND & DIAMOND GRADING 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)
Cleavage (Cl) - answer- Large, severe, straight break along a plane of atomic
weakness; considered an inclusion. (Assignment 10)
Cleavage plane - answer- Plane parallel to a possible crystal face, where a diamond
can split cleanly when struck. (Assignment 7)
Cleaver - answer- A person who cleaves, or splits, a diamond along a cleavage plane.
The cleaver might also be responsible for planning the fashioning of a polished gem.
(Assignment 9)
Cleaving - answer- Dividing a diamond into two or more pieces along a cleavage plane.
(Assignment 9)
Cloud (Cld) - answer- Many tightly grouped pinpoints that might be too small to
distinguish individually at 10X but together have a hazy appearance. (Assignment 10)
Color center - answer- Structural defect that influences an object's absorption of light
and can cause its color. (Assignment 12)
Conflict diamonds - answer- Diamonds used to finance violence and terror. (Assignment
3)
,Consignment - answer- A selection of goods loaned to a dealer by another wholesaler
or manufacturer. (Assignment 20)
Covalent bond - answer- A chemical bond formed by two atoms sharing electrons.
(Assignment 7)
Craftsmanship - answer- The care that goes into the fashioning of a polished diamond,
as confirmed by its finish. (Assignment 15)
Cratons - answer- Ancient, large, and stable parts of the earth's continental crust.
(Assignment 4)
Critical angle - answer- Angle between the normal and the maximum angle of refraction,
which is the largest angle at which rays inside the diamond can escape. (Assignment 8)
Cross worker - answer- A person who performs the cross-working operations during
diamond polishing; sometimes called a cross cutter. (Assignment 9)
Cross working - answer- Placing the bezel and pavilion facets on round and fancy
shapes. Sometimes combined with blocking, especially on smaller stones. Also called
cross cutting. (Assignment 9)
Crown angle - answer- The angle formed by the bezel facets and the girdle plane.
(Assignment 14)
Crown height percentage - answer- The distance from the girdle plane to the table,
expressed as a percentage of average girdle diameter. (Assignment 14)
Crust - answer- The surface and outermost layer of the earth. (Assignment 4)
Crystal - answer- Solid matter with atoms arranged in a regular, repeating pattern.
(Assignment 7)
Crystal (Xtl) - answer- A mineral crystal contained in a diamond. (Assignment 10)
Crystal planes - answer- Internal directions parallel to a mineral's unit cell surfaces.
(Assignment 7)
Crystal shape (form) - answer- Geometric shape of a well-formed crystal. (Assignment
7)
Crystal structure (lattice) - answer- Regular, repeating arrangement of atoms in a
mineral. (Assignment 7)
, Crystal systems - answer- Categories of crystals based on their symmetry and internal
structure. (Assignment 7)
Crystalline - answer- Composed of crystals or related to crystals. (Assignment 7)
Culet size - answer- The size of the facet at the bottom of the diamond where the
pavilion mains meet. (Assignment 15)
Cuttable rough - answer- Diamond rough with good enough size, shape, clarity, and
color to produce a polished stone suitable for use in jewelry. (Assignment 5)
Cutting center - answer- A city, region, or country with a large number of gemstone
manufacturers. (Assignment 3)
Cutting style - answer- The arrangement of a gem's facets. (Assignment 16)
Darkfield illumination - answer- Lighting of a diamond from the side against a black,
non-reflective background. (Assignment 10)
Dense media separation - answer- A recovery process that separates diamonds from
lighter material. Also called heavy media separation. (Assignment 6)
Depth of field - answer- The distance that's clear and sharp above and below a point
you focus on with a magnifier. (Assignment 10)
Design - answer- A diamond's physical shape, including its proportions and durability,
determined by decisions made during the fashioning process. (Assignment 15)
Diamantaire - answer- A knowledgeable, experienced, and successful person, usually a
dealer or manufacturer, in the diamond trade. (Assignment 20)
Diamond pipeline - answer- The path diamonds followed from the mine to the
consumer. (Assignment 2)
Diamond simulant - answer- Any material that is not diamond or synthetic diamond, but
which imitates a diamond's appearance and is used in its place. (Assignment 18)
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)
Bearded Girdle (BG) - answer- Very small feathers that extend from the girdle surface
into the stone; can result from the cutting process. (Assignment 10)
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