Glossary

Acrylic . Acrylics are a type of thermoplastic and include transparent and opaque in varied colours.  Some commonly-known acrylics are lucite and plexiglas.

Amber is translucent fossilized tree resin (from conifers), a natural hydrocarbon that comes in many colours, including yellow, reddish, whitish, black and blue.  Although not mineralized, it is often classified as a gemstone.    As is used to be a soft sticky tree resin, amber can sometimes contain insects and even small vertebrates.  Pressed amber consists of small pieces of amber that have been fused together to form a larger piece.

Amethyst – See chart below under quartz.

Aurora Borealis rhinestones have a special iridescent finish that shines with many colours.  The iridescent surface is a result of a very thin layer of metallic atoms that have been deposited on the lower surface of the stone.  This process was invented in 1955 by the Swarovski company, together with Christian Dior.  Aurora Borealis tends to reflect whatever colour is worn near it and it is named after the Aurora Borealis atmospheric phenomenon, also known as the Northern Lights.

Briolette (or drop cut) is a pear-shaped cut gemstone with triangular facets on top.  This type of cut makes a nice pendant.

Cabochon  A cabochon is a stone that has been shaped and polished, usually with rounded domed surface with no facets with a flat bottom.  Cutting “en cabochon” is usually applied to opaque gems whilst faceting is usually applied to transparent stones.

Cat’s Eye (chatoyant chrysoberyl) is a honey coloured stone which is usually cut as cabochons to maximize the distinctive pupil-like effect which gives it its name.

Chalcedony – see chart below under quartz.

Chaton  - A chaton is a stone with a reflective metal foil backing.

Crystal (natural) A crystal is a solid whose atoms, molecules or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions.  Some crystals include quartz, diamond and emerald.

Cubic Zirconia is a lab produced gemstone which looks exactly like a diamond.  It is optically flawless and usually colourless but can be made in a variety of different colours.  It should not be confused with zircon which is a zirconium silicate.

Diasterism  An asterism is an optical phenomenon displayed by some rubies, sapphires and other gems of an enhanced reflective area in the shape of a star.  Two typles of asterism are:

1.        Epiasterism, such as that seen in sapphire and most other gems, is the result of a reflection of light on parallel arranged inclusions inside the gemstone.

2.       Diasterism, such as that seen in rose quartz, is the result of light transmitted through the stone.  In order to see this effect, the stone must be illuminated from behind.

Facet, faceting   Faceting is the cutting and polishing of the surface of a stone.  The facets are the resulting flat surfaces of the cut stone or glass.  Faceting is usually applied to transparent stones such as diamonds. 

Hematite (also known as kidney ore) is a lustrous opaque, blue-black to silvery grey mineral often used in jewellery. 

Labradorite  is a variety of plagioclase feldspar and is a fairly abundant greyish mineral that has flashes of colour, usually green, blue or red after it is polished.  There is a darker variety of labradorite (called “black moonstone”) which has bluish inclusions.  Labradorite it usually cut with a flat surface in order to highlight the flashes of colour. 

Moonstone (orthoclase) is a semi-translucent stone that is made of albite and orthoclase feldspar.  It is usually whitish-blue but can be colourless, yellow, orange, grey or even reddish.  Moonstone is usually set as a cabochon.  Adularia is a common type of moonstone and another type is Oligoclase.  Labradorite and albite are rare forms.

Mother-of-Pearl, also known as Nacre, is the coating on the inside of oyster shells.  It is strong, resilient and iridescent.

Prong setting refers to the use of metal projectons or tines, called prongs, to secure a gemstone to a piece of jewellery.  A prong setting is one component of what is known in the jewellery business as a head, a claw-shaped type of finding that is welded or soldered to a jewellery item in order to mount a gemstone to the jewellery item.  The head is usually made from some type of precious metal such as gold, silver or platinum.

Quartz is the most abundant mineral in the Earth’s continental crust.  Pure quartz is colourless or white.  Coloured varieties include rose quartz, amethyst, smoky quartz, milky quartz and others.

Major Varieties

Pearl  A pearl is a hard roundish object produced within the soft tissue of a living shelled mollusc.  The ideal pearl is perfectly round and smooth, but many other shapes of pearls occur.

Rose Quartz is a type of quartz which exhibits a pale pink to rose red hue.  This mineral is often carved into figures as it is usually too cloudy to use a gemstone so those used in jewellery are more rare. 

Swarovski is the luxury brand name for a range of precision-cut lead crystal glass and related products.  The founder of the company, Daniel Swarovski developed a new technique for faceting glass crystals, creating a sparkling, diamond-like “chaton”.

Turquoise is an opaque, blue to green mineral that is a hydrous phosphate of copper and aluminium.  It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue.

Zircon (zirconium silicate) is a mineral.  Its natural colour varies between colourless,  yellow-golden, red brown and green.  Not to be confused with Cubic Zirconia which is synthetic substance with a completely different chemical  composition.