There are seven main
types of opal and opal substitutes that are distinguished in the opal market.
Within each of these main types are various sub types. By far the most common
type of opal in the market is a natural solid stone. The next most common is
a triplet. Doublets are becoming more popular as they provide the show of a
natural stone at a fraction of the price. Boulder Opals have grown rapidly in
popularity, often rivaling the best solid opals in beauty and price The other
types, including synthetics and simulants, are gaining a foothold in the market,
particularity in inlay jewelry, because of the recent reductions in supply of
natural solid stones. One must be careful to correctly determine the type of
opal. Here are some definitions to help you in identifying each type of opal.
Natural Opal: A natural
opal is a stone w hich has not been changed from its natural state in any way
except to be fashioned into a gemstone through cutting and polishing.
Treated Opal: A treated
opal has had some foreign material introduced into the stone. Unusually the
treatment is a dye used to darken an opals. Increasingly, treatments are being
developed to stabilize an opal that has cracked or might crack in the future.
Synthetic Opal: A
man-made or laboratory-grown material that has the same mineral content as natural
Opal Simulates: Opal
simulates are man-made materials that have the general appearance of opals-including
a play of color in some cases-but are made of a different material that the
silica balls of natural opal, or have significant amounts of non-silica such
Common Opal | Crystal Opal | Fire Opal | Gem Opal
opal, which displays "opalescence" (spectral color, iridescence
that changes with the angle at which the gem is viewed), is the kind
of opal with which most people are familiar. There are three major kinds:
Opal - White opal is an opaque stone in which the colors appear
as flashes or speckles.
Opal - Black opal contains fire with a dark body color. These are
less common and tend to be costly. These are the investment high
quality opals !
Organic Material - Opalized organic material may consist of wood,
plant stem, bone or shell that has been petrified under extremely
opal, the next most costly type of opal, is transparent with flashes
of color. It is highly valued for the brilliance of its colors and the
fact that many layers of color can be seen within the stone.
unusual type of opal is boulder opal, which has opal with an ironstone
host rock matrix which creates a natural dark background to view its
fire. These sometimes occur in "splits," a matched pair of
opals created when a price of boulder opal is split along the opal vein.
These are particularly favored for earrings, since they are mirror images
of each other.
opal is transparent or translucent with an orange or red body color.
Fire opals are named for their reddish color but are opalescent. Be
careful not to misinterpret the term "fire" as iridescence,
because in precious opal (with a play of iridescent color) the play
itself is also called fire. Much of the world's fire opal is mined in
Opal is rather opaque with no spectral play of color. Many names are
used to describe common varieties. Among these are honey opal, milk
opal, and moss opal. Examples include milky agates and certain "petrified"