Here is a list of the most frequently asked questions we have answered over the past 25 years. If you have a question that isn’t answered on this page, why don’t you drop us an email.
What factors determine value?
Bottom line: No matter what is for sale, assuming a transparent market, the sale price will never exceed what a buyer is willing to pay. HENCE, DEMAND AND SUPPLY, and a willing buyer are what make the market’s final price. In the case of opal, it is a very small market with only a few players — meaning miners, brokers, resellers and endpoint retail buyers. For a detailed look at the factors that influence value in the opal market click here also check out our Buyers Guide
What are opal’s physical characteristics?
Soft. On the Mohs scale of hardness opal measures just above glass: glass= 4-4.5, opal= 4.5-6. Most Australian Opal runs 5 to 5.5; however, Brazilian opal runs closer to quarts at 6-7. Its fracture pattern when broken is hook shaped. When it crazes, it looks like the picture on our site or like a tempered front window in a car
How do I know the opal will not crack or craze?
Actually, you and everyone else DO NOT know. If they say they know, then they are misguided, misinformed or overly confident. The only test is the test of time. Old time Virgin Valley miners just threw the rough on a hot tin roof and left it there for a day or so. If it crazed it would not cut; if it stayed together, then they had a stable cutter. Best idea is that crazing is caused by the percentage of water in the opal. That makes sense. If you measure the percentage of water in an opal you can make a logical guess. Generally, the more water over 5-6% the more likely the stone will crack or fracture. (Weight in air minus weight in water equals percent water). The best way to judge whether or opal will crack or craze comes from experience and trusting the seller.
What kind of machinery cuts opal best?
Diamond- which cuts with the lowest heat. Equipment that has a speed control so that you can carefully control the rate, and hence the heat, at which you cut and polish the stone. Click here to see some of the tools and equipment that we use and recomend.
Can I cut opal without machinery?
Yes. Opal can be shaped with sandpaper (wet & dry) going from 240 to 1200 grit. It can then be polished using optical polish on leather.
Is opal an investment stone?
Yes, in gem quality. Also unique stones (fire patterns and unique colorations). See chart.
How do you judge the yield on a rough stone?
A rough stone should yield 20% or better of it’s volume once it’s cut. For example, a rough five gram stone should yield a five carat cut and polished opal. A rough stone which only yields 5% of its volume is a poor yield.
What is the value of rough opal versus cut opal?
If you buy rough opal and cut it yourself, you should be able to appraise the cut stone at five times what you paid in the rough condition.
What causes the play of color in opals (the fire)?
Click here to learn more.
Why is opal kept in water?
For display only, since the refractive index of water and opal are very close. Opal in water will simulate what opal will look like when it is polished. Otherwise, it shoul be kept dry.
Do you buy opal in Australia?
We buy our opal from the miners directly- in the comfort of our living room- negotiations favor us that way. That helps keep our costs down. Imagine what our price would be if we had to apply the cost of the trip to Australia or Brazil to each ounce of opal that we buy! You don’t have to imagine very long…just look at the prices of our competition and you will see what we are talking about.
How do you store opal?
Store opal safely, well padded.Remember that the hardness is about the same as glass. Rough opal can be stored wet or dry on a shelf, in a drawer, etc. Cut and polished opal should be stored where it will not be subject to banging or scratching by harder materials like gold, diamonds, garnets, etc.
Is it OK to put opal in a safety deposit box?
Only if you place the opal in water, or in a container that is hydrated with a wet/moist paper towel. Safes that hold safety deposit boxes have their air dehydrated to one half of one percent, and opal may lose water through the dehydration process.
Can I soak opal in…
…GLYCERINE? NO. Glycerine is hydrophilic and can draw water from the stone.
…OIL? NO. It is also very hard to clean off.
…WATER? YES. But why?
…WET TOWEL? YES. But why?
Why does the fire disappear on rough opal until you put it in water?
Water has the same refractive index as polished opal, so rough opal in water is a preview of the cut and polished opal. If the opal type is cachalon, which is chalky and dry,when wetted, it absorbs the water and shows fire. The reverse occurs when it drys out.
How do I know the opal I buy will be stable
You don’t! However, the water percentage in the opal is a good indicator. See the note above. Ultimately, your best bet is the reliability of the source…the person you buy from. Most reliable miners know if the opal is coming from a reliable zone which is dry enough to be stable
What does stable mean?
Stable means that the opal, under normal heat and climactic conditions won’t crack or craze.
What is our return policy?
We will replace a parcel that goes bad within 30 days after purchase, but before cutting and grinding…once you cut or grind it you assume total responsibility.
How can you buy from us through the mail?
Click here if you would like to contact us. We will be happy to correspond with you. Let us know what you are interested in, and we will contact you by phone for payment information.
What is opal?
Click here to learn more.
In what countries is opal found?
Australia, Brazil, Java- Indonesia, Virgin Valley- NV, Gabbs- NV(blue), Boise- ID, Oregon (blue), Mojave- CA, Canada, Ethiopia, Austrai, Honduras, Mexico.
What different kinds of opal are there?
Potch/common (desirable if translucent red, yellow).
conc: Replacement of organic material, can be partial.
cachalon: A chalky base that sticks to your tongue.
Faceting: Translucent material with fire that can be faceted like diamonds.
How is opal formed?
Click here to learn more
Where are opals found?
Alluvial stream bed or alluvial field deposit, through the erosion processes, and in various strata. In gas pockets in Idaho and thunder eggs in Oregon. Fossil (opalized) shells and dinosaurs (NV, Australia). Wood replacement or other plant replacement (NV, Australia). Opal forms in cracks of hard rocks, i.e. Boulder Opal (ID, Australia). Rhiolite matrix and sandstone matrix (Honduras). There is also man-made opal.
What is cracking and crazing?
Crazing is like when a rock hit an automobile windshield…the glass shatters like a spiderweb, but is still held together. Cracking means that the piece comes apart or has the potential to come apart.
Why does opal crack or craze?
It can crack or craze naturally, if the water content of the opal is too high. Or, if it is banged around improperly, set into jewelry improperly, or during cutting or polishing if it gets too hot.
What are Opal’s characteristics compared to diamonds?
Diamond is hard/brittle…10 on the Mohs’ scale
Opal is soft/brittle…4.5 to 6 on Mohs’ scale
Can I keep opal in a jewelry box?
Yes, but don’t throw it in with harder stones and metal. Treat as a very fine gem. Place pendants in pendant holders and rings in a ring rack.
Opal is NOT bad luck if it is not your birthstone! This myth was perpetuated by diamond dealers in the late 19th century because opal was diamond’s biggest competitor.
Why buy from people who deal direct from mines?
Generally, opal is more expensivewhen bought at the source. We have peoplewe buy from who know the field, the mine depth, and how it is mined. There is also a historical perspective on some fields as far as stability is concerned. For instance, opal from the Mehi field or 19 mile is considered unstable. Also, opal found more than 50ft deep is not considered as stable, due to the release of pressure. Pressure keeps the water in the opal until it is brought up from the mine. Then it can crack or craze as the pressure releases. That’s why we buy from long term associates who know or try to find out where exactly the opal is mined.
Why use epoxy instead of dopping wax?
A miner from the Lightning Ridge opal field in Australia sent five parcels of rough opal to five different cutters. Those that used dopping wax had the highest cracking rate. Those that used epoxy had the lowest cracking rate.
Why buy in the in United States
First, there is less waiting time. We send a couple of parcels to our clientsand they can choose their lots. Buying in Australia takes a long time, and many customers that buy from Australian sources who are unhappy do not return bad batches since it is too much trouble…even though there are many ethical Aussies who care if you find a if you find a problem and will take care of you.
What are fabricated opals?
Triplets: Opal is sandwiched and glued between a backing and a quartz cap.
Doublets: A thin piece of opal is glued to a backing or potch, jade, glass, etc.
Overlay: A doublet with a bolder opal backing.
Mosaics: Many small pieces of opal glued on a black surface together using small pieces
Intarsia: Opal is combined with various materials; lapis, malachite, sugilite, jades, etc., in geometric patterns or other designs (like inlaid wood).