Possibly no stone used in jewelry manufacturing today spans such a wide range of prices as opal. At the low end of the pricing structure is milky opal with a few small flecks of color. These inexpensive stones are widely used in silver and light weight gold, or even gold plated jewelry.
At the other extreme and commanding top dollar are Lighting Ridge, Australian stones. Fine examples of these gems have a dark to black crystal base, and a full range of colors displayed in random patches that seem to be suspended within the stone. Fine Lightning Ridge stone can sell for as much as diamonds.
Thin sheets of opal are sometimes glued to a base material and called "doublets". If a clear cap is added to this doublet, a "triplet" is created. Boulder opal are when a portion of the natural ironstone base rock is left attached to the opal as it was taken from the ground.
Opal is a somewhat soft stone, and care should be taken in wearing opals. However, many antique opal jewelry pieces have survived the test of time. Primary opal sources are Australia, Mexico, and Idaho, U.S.A. Also accepted as an opal birthstone substitute is Tourmaline (see June, pearl-tourmaline).
