4 (or 5) C's
  • Carat - This term, derived from the carob seed (each weighing 1 carat), is used to describe the weight of a stone. It is equivalent to 1/5th of a gram.
  • Clarity - The presence (or, prefferably, absence) of flaws in a gemstone.
  • Colour - The colour of the light refracted from the gemstone.
  • Cut - The style in which the facets of the stone are created. Some of the most popular cuts include the brilliant cut and the emerald cut.
  • Canadian - The fifth "C". Usually used to describe diamonds that are mined in the Northwest Territories, Canada.
Alloy A combination of two or more metals, usually a large quantity of one metal and small quantities of any other metal(s). The other metals are added to increase strength, change colour or to reduce the cost of the metal.
Amethyst Amethyst is a member of the quartz family, and is well-known for its bright purple colour. The name comes from the Greek for "not to intoxicate". The Ancient Greeks believed that drinking from amethyst cups and wearing the mineral would prevent the bearer from drunkenness. It rates a 7 on the Mohs scale (see below), and is the birthstone of the month of February.
Aquamarine A gemstone belonging to the beryl family, aquamarine has a distinct light blue or turquoise colour. Its name comes from the Latin for "water of the sea". Aquamarine is the official gemstone of Colorado, and is the birthstone for the month of March.
Bezel A type of stone setting that uses a "wall" of metal to surround the stone.
Brilliance The amount of light reflected back to the viewer.
Brilliant Cut One of the most popular, if not the most popular, cuts of diamonds. The number of facets totals fifty-eight.
Butterfly Back An earring backing, also known as a scroll back.
Cabochon A stone that has a rounded, smooth surface.
Channel Setting A way of setting stones that forms two walls of metal, like a channel, to hold in stones.
Colours of Gold Yellow, green, red and white are produced by adding silver, copper and nickel as alloys.
Culet The point bottom-most of the pavillion of a gemstone.
Diamond Diamonds are the hardest natural material known. They have been treasured since their use as religious icons in India, about 2 500 years ago. They have a glassy appearance to them, and refract light in many directions. Their appearance and quality is commonly judged by the 4 C's (see above). While most commonly known (and sought after) in their colourless form, they come in many different colours, including red, pink, yellow, green and black. Diamonds are the monthly birthstone of April.
Dispersion The rainbow effect of light passing through a stone and splitting into different colours.
Emerald Emeralds, by weight, are the most valuable gemstone in the world. They come in various shades of green and blue-green, and are a 7.5 on the Mohs scale (see below). Emerald belongs to the beryl family. Another well-known gemstone in this family is aquamarine. Emeralds are the birthstone of the month of May.
Flawless A gemstone with no visible imperfections at 10X magnification.
Garnet Garnet is a family of stones with a hardness ranging from 6.5 to 7.5. Red garnets (almandine and pyrope) are the most common, but other garnets can be found in a full rainbow of colours, blue being the rarest. Garnets are the birthstone of the month of January.
Ideal Cut A set of proportions discovered in 1919 by Marcel Tolkowsky, thought to produce the greatest brilliance and dispersion in a round, brilliant cut diamond.
Inclusion Foreign bodies, cracks and other artifacts on a gemstone, visible to the naked eye. Stones that have inclusions are described as "included".
Karat A measure of fineness — 24 karat (kt) is fine gold. Thus, 18kt is 18/24 fine gold, and the balance (6/24) is alloy.
Loupe Clean This is another term for "flawless". A gemstone with no visible imperfections at 10X magnification.
Mohs Scale A scale describing the hardness of a gemstone. At the extreme ends of the scale, talc rates a 1, and a diamond is a 10.
Nacre The mother-of-pearl secretions of the mollusk.
Pearl The origin of the word "pearl" is uncertain, however it may have its roots in the Latin for "shell". Pearls are graded based on their lustre (also called "orient") and their purity of surface. Pearls have a hardness of only 3 or 4, and are the birthstone of the month of June.
Precious Metals Gold, silver, platinum and palladium are known as the precious metals or noble metals, in the jewellery trade.
Refraction The bending of light through two transparent surfaces. Light travelling through a gem, then through the air, would be an example of light refraction.
Ruby A ruby is part of the corundum family, with the addition of chromium in its mineral composition. Legend has it that rubies will ward off misfortunes and ill health. Rubies have a hardness of 9 and are the birthstone of the month of July.
Sapphire Sapphire is the name for the gem quality of the corundum mineral and appears in a full spectrum of colours. Sapphire has a hardness of 9 and is the birthstone of September.
Tourmaline Tourmaline has the richest variation in colour of any gemstone. The majority of tourmaline crystals exist in varying bi– or tri–colour combinations; unicoloured tourmalines are rare. Its hardness is between 7 and 7.5, and it is the alternate birthstone for the month of October.
Translucent An object or surface that is partially transparent. Translucency is the middle-ground between transparent and opaque.
Trillian A style of stone cutting that was first created in Amsterdam. It is triangluar or wedge-like in shape, and the corners may be pointed or flattened, depending on the characteristics of the specific stone and the cutter's choice.
Window A gem whose centre has been cut too shallow, producing an effect that lacks brilliance.
Zircon The name zircon is derived from the Arabic "zargun", meaning "gold colour". Zircon should not be confused with the man-made crystal cubic zirconia. It has a hardness of 7.5 and is December's birthstone.