Cabochon
A stone with a convex top and flat bottom. Cabochon shapes are usually used for opaque stones, or softer stones that would easily show scratches in a faceted cut.
Callipers
A tool used to measure the distance between 2 opposing sides of an object.
Carat
- A unit of mass used for measuring gemstones and pearls. 1 carat = 200 mg. A carat is divided into 100 points (each 2 mg).
- A unit of purity for gold alloys (symbol k or kt). For example: 24 is the purest, 18 is 18/24 or 75% purity.
Casting
A forming process where molten metal is poured into a mould, and then allowed to cool and solidify. The solidified component is also known as a casting.
Centre punch
A centre punch is a tool with a hardened tip used to mark the centre of a point. It is struck with a hammer to mark the centre of a hole when drilling holes in order to prevent the drill bit from 'wandering'.
Channel setting
A row of gemstones held side by side between two long tracks of metal.
Chevron setting
V shaped claws securing a gemstone in place at the points of a marquis cut stone.
Charcoal block
Used as a soldering surface, charcoal reflects heat weel and induces a reducing atmosphere which helps prevent excessive oxidation of the metal.
Chasing
A cold working process where punches and hammers are used to refine a design on the front of the work by sinking the metal, and is the opposite of repoussé.
Chenier
Small gauge metal tubing used to enhance a design or as part of a hinge.
Claw setting
A set of metal prongs used to securely hold a gemstone whilst allowing the maximum amount of light to shine through the stone.
Clarity
One of the four Cs of diamond quality. Most diamonds have some inner impurities. The number, size and darkness of these determine the clarity.
Cold connection
Any method of joining two materials together without the application of heat, such as rivets, tabs, folds, screws or bolts.
Collet
A setting used to hold a gemstone in place on a collar of metal, secured in place with claws.
Colour
One of the four Cs of diamond quality. Completely colourless diamonds refract the most light. Slightly tinted diamonds are worth less.
Copper
A ductile and malleable red coloured metal. Often used for practice pieces due to its low cost.
Countersink
Either a conical hole cut into the metal, or the tool used to create the hole. A common use is to allow a countersunk screw head to fit flush with the surface.
Creasing hammer
Used to form radial creases in a metal disc.
Crown
The upper region of a faceted gemstone.
