In this, final instalment, we learn what factors are involved when determining value of an Opal and meanings behind some of those terms used throughout my 7 part series.
When determining value of an opal, several factors are involved:
Type of opal
Brightness of fire
Background (base) Colour:
Solid precious opal is more valuable than a doublet or triplet, and black opal is more valuable than boulder opal, and so forth. The darker body colour, more valuable gem.
The clarity of opals colour is critical when determining value of opal. Opal is graded according to its colour, with red fire being most rare, followed by green/orange, green/blue, blue, and finally, purple. However, brilliance and clarity of colour, along with proportional pattern are main decision makers; a brilliant blue/green opal can cost more than a dull red. An opal displaying a bright “pinfire” pattern can cost more than a cloudy open pattern of similar colouration.
Nearly all opal displays some type of pattern, with no two opals being alike.
The various patterns are:
The most prized of all nice patterns and its name is derived from its likeness to floral dress material.
Closely resembles a mass of pinheads in different colours.
Mobile rolling Flash:
Consists of one colour, which travels across part of or all of stone as it is moved.
As name suggests, resembles an artist’s palette.
Opal should be free from cracks and flaws.
Agitator: Modified cement mixer used to wash dirt away
from precious opal.
Boulder Opal: Formed in cavities and cracks of Ironstone,
usually from Queensland, Australia.
Black Opal: Naturally occurring solid opal with a coloured
face and black backing.
Blower: A large truck mounted vacuum cleaner used to
suck dirt to surface.
Cabochon: The rounded surface of a cut stone.
Crystal: Transparent/translucent opal.