According to Paul Downing, PhD, an acknowledge expert in all aspects of opal — from mining to cutting to setting into jewelry.
Most commercially set opals that you see in jewelry stores were set improperly, during Downiing’s heyday in the 1990s, and I mention his strictures here because you never know when a jeweler might not go back to the bad old ways necause it takes less time, even if the jewelery suffers.
Downing points out that opals are not too fragile to wear, if only they are set properly.
Some jewelers set opals in mounting reserved for faceted stones, like diamonds. And since opals are more fragile than diamond, they do indeed break when set in that manner.
The most fragile part of a cut opal is the bottom edge, so to prevent the gem from cracking in its setting, it should be completely surrounded by, or nestled in, metal. On no account should you purchase opal sitting up in a set of prongs, with no gold or other medal around it.
If you have precious opal atop either common opal or another substance, is it considered a doublet? No – not if they are formed naturally together.
Natural opal – natural precious opal cut to include common opal or potch in one piece
boulder opal - opal cut to include ironstone, rather than common opal or potch)
Doublet – A natural opal assembled with common opal, potch, or any other material
Triplet - the same.
Some dealers attempt to sell assembled opal and ironstone as boulder opal – don’t be fooled!
A wavy line between the two indicates a natural boulder opal. A straight line = an assembled boulder opal, i.e., a doublet.
The Smithsonian Institute was founded in 1855, after a bequest by a British scientist, Charles Smithson, upon his death in 1835. (How the Institute came into being is a fascinating story in itself.)
Today. the Institute has 19 museums, most of them located in Washington DC. The Air and Space Musuem is perhaps the most famous, but its the National Gem Collection that interests here.
Several pieces of opal jewelry are on display in the collection (and photographs of them appear in the book The National Gem Collection, published by the Smithsonian Institution.
The two most famous pieces are an opal and gold necklace designed by Louis Comfort Tiffany in about 1915-1925. It is accented with brilliant green demantoid garnets from Russia. The black opals are from Lightning Ridge, Australia. Ruth and Townsend treadway gifted it ti the Smithsonian in 1974.
There’s also a peacock brooch designed by Harry Winston, Inc. It features a 32-carat black opal from Lightning Ridge as the peacock’s body, with a head and dangling tail encrusted with smaller sapphires, rubies, emeralds and diamonds. Harry Winston gifted it in 1977.