BLACK OPALS FROM NEVADA:
The rarest and most valuable opals are bright on black. Black background opals show off the rainbows of fire, or play of color, the best. Super gem bright opal is that which you can’t see through to the background opal color. A lot of “black” opal is some background behind a bright crystal.
The Virgin Valley gem opal production is only a tiny percentage of the commercial opal industry. BUT, our cut blacks play of color is unmatched by any other opal in the world. The different formation makes for a style of fire play that’s unusual to say the least and comparable to most. It also makes many craze when dried too fast, possibly from the charcoal or manganese contained in them, or it could be the sulfur, who knows. We just know we lose most to drying somehow and a small percentage is as good as any opal on earth for use as gemstones.
Specimen gem rough can be just optically stunning, while being physically interesting to boot, with natural pseudomorph forms. That means that we get perfect casts in precious opal of ancient plants such as twigs, pinecones, and branches that range up to log opals that weigh pounds.
Miners say “specimen” a lot because a large number of the bigger pieces are bought for mineral displays, not for cutting rough. When dried, most large opals become small opals or cracked, as the water that is an essential part of them evaporates. All opal eventually loses this water they say. (Australian opal included say their scientists). I’m not handing you any BS here and have been complemented.
Black twig cast with excellent definition and play of color. This specimen from our mine is on display at the Winnemucca BLM office.
They are cut up for use in jewelry only after being dried for a period of time. I dry mine for months before even worrying about what to cut. If you want to save the specimens at the first cracks you have to watch them for a few hours at least.. I dry most of the wood with opal specimens when found because the wood matrix holds the pieces together after being washed off. Out of water and onto a board in the desert…torture is a good description of the proving process I use. Then they are dry and colorful cachalon opal that looked good damp is now whited out after losing it’s exchangeable water content. Cut the small pieces and marvel at the big ones wet. The blacks here are rare as down under and with much more root beer glass found than the crystal opal over black potch blacks. Still, the dark crystal and jelly opal can be huge and commonly weigh ounces to pounds. We also don’t move near the amount of material they go through to get “mine run”.
In 2003, Leah found this large black opal “core” on our mine. A core is in a hollow limb cast in the clay, empty but for the opal mass laying in the hole un-attached. It weighed 190 Grams in 2 pieces. The limb was segmented prior to precious opalization not broken. A N1 black crystal opal. It has that distinctive Nevada burning fire on all sides and reddish multicolor harlequin on the top and bluish multicolor harlequin on the bottom with a brightness of 3 out of 5. This opal measures 4 1/2″ by 1 3/4″. The Asteria harlequin pattern is visible from all sides giving a different view of the bars, tubes, flames. Unpolished, it has red, green, blue, and yellow rainbow rolling bars. A 1″ wide color band 360 degrees around.
Swordfish Mining has several large opal specimens both dry woods and wet casts for sale. Several are larger diameter opal limbs with bright veining where only the crack were filled with gems. Any of the never dried wet opals may change appearances on drying and are therefore sold as specimens only with no assurances of dry ability or cut ability.
If one dries good – congratulations you beat the odds. If not, you’re the one who dried it out, and what you see is what you have. They can now be made into something that the drying question has been answered. You can restore it back as a specimen by some sort of treatment and then polishing it if desired. Immersing them in Glycerin or mineral oil wets them and hides the fractures well, but is considered treatment. If they are in water that is just storage. You can polish or have them polished while wet without ever drying them out to increase their eye appeal.
Wet pieces (over 1″ chunks) start at $25 each. This rough all has precious play of color except the occasional wonderful specimens of contra luz opal or pastel glowing specimens. You must state you want a non precious one before I would send a pure specimen. None of these lower cost opals are solid blacks with no cracks. The black is only a minor part of most stones and is usually not as bright as the white or crystal. Wet chunks are displayed in domes or closed jars unless gambling on that they might dry to be polished and set. They all have some play of color showing and not skin to skin either.
Contra Luz is where the play of color shows with the opal held up to the light. A good quarter of all the clear non-precious areas have contra-luz color. The precious and common areas usually don’t show contra luz play of color when still wet. Opals are very difficult to photograph well and seldom look just like the picture. IF they dried pieces, are generally sold at a huge discount of the proven dry rough cost. Dealers don’t open domes to split up the parcel. Any single stone is individually priced by how rare it is from experience, not by comparisons to what others are willing to sell one single one for. That’s the gemstone business; All individuals out for themselves, so buy that one offered by others and don’t beat my chops about they are sold out and don’t have more. While buying it you find out what they have to say about it to rate their opinions and skill in valuing rough and their honesty in sales.
One closing note. I’m tired of calls about NOT MY OPAL. I’m in business to sell my products, not to help every other recreational digger try to compete with me. Please don’t ask me to provide you with free appraisal services. That is normally a 10% of the appraised value fee from any certified insurance appraiser.
Mr. Liddicoat of the Gemological institute of America GIA stated (more or less):
“If there was a scale of difficulty in the understanding and appraisal of gemstones, then diamonds would rank as the easiest at #1 and opals as the most demanding at #10.”
Opal is: the hardest gemstone to find, to mine, to properly cut, and to grade and price.