Page 15 - 2018 Coober Pedy Visitor Guide

Base Colour. Black opal (a gem with a
dark base) is more valuable than crystal
opal (almost transparent) which in turn is
more valuable than the white or milky opal.
Dominant Colour Red fire opal is more
valuable than a predominantly green opal,
which in turn is more valuable than a stone
showing only blue colour. by Joe Bird
Colour Pattern Harlequin opal, where
the colour occurs in defined patches, is
generally more sought after and valuable They are classified:
than pin-fire opal where the colour Solid opals that nat-
generally appears in small specks. urally occur in one
Once the opal has been classed in various piece.
grades, each grade is weighed in Troy Doublet a 2 part
ounces then valued at a rate of dollars per stone consisting of a
ounce before being placed into a bag. precious opal glued to
Each bag is then identified by grade and another stone, either
weight. Collectively these bags are potch or some other
known as a PARCEL of opal. material like glass or
Cut opal is valued at a price based on qual- iron stone.
ity, brilliance, clarity, variety of colour and
pattern per carat weight. Triplet a three part
Opals may be cut and polished in a number stone with a precious
opal centre, a clear top
of ways, depending on the nature and and darkened base,
thickness of the colour band. usually glass or potch.
Opals are the softess of the precious gems
and need delicate care when shaping and
polishing a stone. Always ensure your
jeweller is familiar with opal when taking
your jewellery for polishing.

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by Wayne Borrett

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