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Synthetic Opal
Synthetic opal came on the market in 1974 and
is produced in the two basic varieties of ornamental value,
with a light or dark ground.
Appearance It matches the appearance of noble
or precious opal precisely, with patches of iridescence on
a milky white or deep blue to smoke gray or blackish ground.
Naturally, the contrast between the background and colored
patches produced by light diffraction is stronger in the dark
variety (see the section on natural opal). It is generally
cut into oval or round cabochons; more rarely, into less regular
shapes, the thickness not usually exceeding 5 millimeters.
Recently, however, polished, spherical necklace beads with
a diameter of 7-8 millimeters and more have been manufactured,
proving that it can be produced in greater thick
Distinctive features It is very hard to distinguish
from natural opal. Only under a microscope can one see a difference
in the patches of color, which have a minutely tesselated
appearance like lizard skin, never seen in the natural variety.
As a result, the edges of the colored patches are also minutely
sinuous and indented.
Cost The white opal is less expensive than
the black, which costs as much as some natural secondary gems,
but less than the most expensive synthetic products.
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