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Glossary
Antique: Old, as opposed to new. Generally understood to refer to items over 100 years old, but is variously
defined by jurisdiction.
Appraisal: 1) (noun) The act or process of estimating value; an estimate of value. 2) (adjective) Of or
pertaining to appraising and related functions, e.g. appraisal practice, appraisal services.
Appraiser: One who is competent to estimate the most fully appropriate value of a specified type of property.
Brilliance: The brightness of a gem; the amount of light that enters the stone, refracted internally, and
reflected back out. Diamonds give off both white light (brilliance) and coloured light (dispersion, or
“fire”).
Chronometer: A movement certified by maintaining precise time under rigorous testing.
CIBJO: Confederation Internationale de la Bijouterie, Joaillerie, Orfevrerie, des Diamants, Perles et Pierres. A
European regulatory body encouraging many aspects of International cooperation in the jewellery
industry but in particular, enforcing correct nomenclature and definition.
Condition: The physical description of the property relating to its completeness for performing an identified
role. Impairments could include damage of any kind, loss of components, wear and tear and
inappropriate or unacceptable repairs.
Cut: 1.) In gems, a fashioned gem, as opposed to a rough or uncut gem. 2.) The shaping and polishing of a
gemstone. 3.) The proportions to which a gem is fashioned. One of the “four C‟s” in diamond grading
Dial: The plate behind the hands of the watch. Sometimes enamelled and hand-painted, and sometimes with
gold markers or diamonds for numbers.
Diamond: Hardest of all known natural substances, composed of pure carbon.
Dispersion: Coloured light given off from a gem caused by the prism effect of the cutting angles on white
light. Commonly referred to as “fire”.
Emerald: Green, variety of beryl, coloured by chromium or vanadium.
Fluorescence: A property possessed by some substance to change invisible ultra-violet rays into visible light.
Useful in identify the origin of certain gems.
Gemstone: To be classified as a gemstone, a mineral (or occasionally an organic material) must be beautiful,
durable and rare.
The beauty of a gemstone depends to a large extent on its optical properties. The most important of
these being the colour and the way the gemstone refracts light. Other important factors are fire,
brilliance, lustre and transparency.
Durability is the ability of the gemstone to withstand everyday wear without breaking or scratching. If a
stone is so soft that it cannot be set into a piece of jewellery then it cannot truly be regarded as a
gemstone.
The final factor in determining whether a mineral or organic material is regarded as a gemstone is its
rarity. Large fine quality gemstones, i.e. emeralds, are much rarer than small lower quality stones of the
same type.
GIA: Gemological Institute of America
Gram: Unit of weight in the metric system equal to 15.432 Troy grains, often used to weigh gold chains.
Guilloché: [gee oh SHAY] lit., engine-turned. Machine-engraved decoration on metal, over which translucent
enamel is often applied (called
guilloché enamel
)
Limiting Conditions: Conditions that materially affect the appraisal process and, as a consequence, the value
conclusion. Not being able to personally inspect the property because it has been destroyed by fire is a
limiting condition. Inspecting diamonds while mounted is a limiting condition.
Melee: 1.) A parcel of round diamonds up to about ¼ carat. 2.) The accent diamonds in a piece of jewellery.
3.) In rough diamonds, octahedral and irregular octahedral crystals under 1 carat.
Movement: The works of a watch exclusive of the case and dial.