A B C D E F G H I J L M N O P R S T V Z ALLcabochon
stone with flat or slightly concave bottom and domed upper part
calibrated goods
a term used by the
gemtrade to denote gemstones cut to standardized shapes and sizes so they can be set in pre-fabricated
settings.
carat
abbr. ct, plural cts; unit of weight, 1ct = 0.2g
cat´s eye effect
see chatoyancy
chatoyancy
cat´s eye effect caused by
reflection of light at needle-shaped inclusions or growth tubes. only visible in cabochon cuts under a single light
source (sunlight, spotlight).


checkerboard cut
cut with no table facet, upper part fully covered with lozenge shaped or square facets


CIBJO
Confédération Internationale de la Bijouterie, Joaillerie, Orfèvrerie, Perles et Pierres or World Jewellery
Confederation. founded 1926 as BIBOAH, re-named CIBJO in 1961. the task of this council is to record trade
practices and nomenclature and to set trade standards accepted worldwide.
cleavage
the tendency of some gems to split along certain crystal planes
colour change
stones may display
different colours under daylight and artificial light; the most prominent colour changing stone is alexandrite, a chrysoberyl variety; the phenomenon also occurs in other gemstones e.g.
sapphire


concave cut
also "millenniums cut", with concave grooves
in the pavilion (the part of a gemstone that lies beneath the girdle)

crown
the part of a
gemstone lying above the girdle
cubic zirconia
"cubic stabilized zirconium oxide", often abbreviated to "CZ", very popular diamond imitation. has nothing in common with natural zircon except
for the element of zirconium.
culet
the facet produced by
cutting off the tip of the stone to prevent damage, old style, usually not found in modern cuts
cushion
cushion shaped cut

A B C D E F G H I J L M N O P R S T V Z ALL