Buying opal jewelry loose in a shop is difficult enough if you don't understand them but to buy them online is a daunting task. You are at the mercy of the salesperson and that is not always in your best interest. But I can help with some advice which will smooth the way.
Natural or Synthetic?
Synthetic opals are man made in a laboratory and will be called "created opals" by most websites. They can make stunning jewelry too. The may also be called "imitation opals."
Solid, Doublet or Triplet?
Let's say after deciding that we want real or natural opals rather than man made opals we now need to decide whether we want a solid opal, a doublet or a triplet.
You may be aware that a solid opal is one piece and is the best and most expensive.
A solid opal which is very thin, too thin to make into a piece of jewelry, will have another piece of black colored opal glue to the back of it to give it strength and to bounce the stone's bright colors. These are doublets and are cheaper than solids and can often look even nicer. We just have to be aware that they are not solid opals.
A triplet is basically a doublet with a dome of clear material such as quartz or glass on the top of it. These are the cheapest of all but often look fantastic. Again we just need to have an understanding of what we are buying.
Doublets and triplets may not be just thin or poor quality opal products which cannot be sold. Sometimes good opal is deliberately cut up into tiny flat pieces and made into doublets and triplets. It is anathema to a real opal lover like me. I have seen these wafer thin pieces cut so thin that when you place them in the palm of your hand they sink into the hollow of your hand. They are then made into lots and lots of triplets from the one original solid opal.
Which is the best Color?
Let us assume that we want a natural, solid opal. The next thing is to think of color. Anything with red in it is going to be the most expensive. Then green is the next expensive and then blue. But, having said that, I have seen plenty of bright blue solid opals which are far nicer and much more expensive than dull pieces of red. So it is a matter of how bright and fiery the actual stone is rather than whether it is red, blue, green or any other color.
What Shapes Should I Look For?
As most good opals come from Australia you are going to see their measurements in millimeters rather than inches or parts of inches. Most opals will be an oval shape. The market over many years has dictated that oval shapes are the most popular. If it is not an oval shape then it will be called a "free form." That means that it is an irregular shape.
Some opals will be round but this is not popular and is the most difficult shape to cut.
This is an important distinction since ovals are more likely to go into a setting that your jeweler already has rather than having to make a setting specially for that free form stone which is going to cost you a good deal more. Possibly twice as much or more as a mounting which has been mass produced and is freely available to your jeweler.
Is size Important?
Read the description of the opal or opal jewelry very carefully. What you want to know is the size firstly. If it is for a ring then you'll be looking for an oval 7 x 5mm, or 8 x 6mm, or 10 x 8mm, or even 9 x 7mm. These are the sizes that your jeweler might have a ring mounting ready made to suit your stone. Otherwise he will have to custom make one.
A pendant size can be anything from 8 x 6mm and bigger. I think that any smaller than this is getting a touch too small for a pendant.
The next thing you want to know is the thickness of the stone. Generally, any opal less than 1.5mm thick is going to be too thin. An opal thicker than 4mm may be difficult to set in a ring.
Of course, I am generalizing here. I have set solid opals measuring 18 x 13 x 6mm in rings but they were large.
What about Inclusions?
Next you want to be aware if there are any inclusions or faults in the top surface of the stone. Stones such as emeralds, sapphires and diamonds have what we call inclusions. If you look closely at the stone you will see some cracks, tiny holes discolorations and other things. These devalue the stone but most times do not make it unworthy of sale.
Opals are different. We don't want any cracks or holes in our opals. It is okay to have a pitted surface on the bottom of the opal or a bit of what we call sand. This is sometimes mixed in with the opal structure and the cutter will make sure that is the bottom or underneath of the opal.
Can an opal be Poorly Cut?
Most opals are cut by miners or their wives. There are very few professional opal cutters. They usually have no formal training in a college or school of some sort. Consequently the cutting is poor.
The problems here are that the stones will not be a perfect shape and might need cutting again to allow them to be made into a lovely piece of jewelry. People who can cut opals well are hard to find in Australia so in another country they are going to be even rarer. Your jeweler will almost certainly not know how to or want to cut opals. So, you should look at the shape of the opal carefully and ask the seller if this will be ready to set into a ring without needing any further cutting.
Does it matter what it weighs?
The weight of the opal is also important. We in the Lightning Ridge area of opal mining in the state of NSW in Australia weigh our opals in carats. A good sized opal for a ring will be between one and three carats. Naturally, there are tiny sized stones which are lovely. I have set 0.3 of a carat many times but if you are unfamiliar with buying opals you will be disappointed with your purchase which will always look big on a website if you have bought a 5 x3mm stone weighing 0.2 carats.
In summary, look for a decent thickness greater than 1.5 mm, a size of 5mm or bigger, an oval shape for a ready made mount, a stone with no visible blemishes and one carat or bigger. You can go outside of these parameters but ask the seller some questions. Remember that opals are very difficult to photograph and it is a good idea to ask the seller if when you turn this stone around will it still have that fiery color?
