IMPORTANT: Anyone who knows me knows that I do not say the following lightly, however I feel very strongly that what these people are doing is wrong (and hurtful to the industry and people buying their jewellery) and needs to be stopped... there is a prominent online jewellery website called www.jegem.com who are saying in their listings that an opal doublet is the same as a boulder opal (here is an example of their listing - Australian Black Opal Doublet (Boulder Opal) Pendant. This is extremely misleading. There is a massive difference in value and quality between a opal doublet and a boulder opal and these people would know it. If they're willing to write such lies then what else are the lying about. I would not recommend doing any business with them. If you read this message please email then and tell them about this site and what I have said. Hopefully if enough people do it then they might stop.
The following is a excerpt from our opal museum tour...
In Australia there are 17 opal fields in Australia. Opal was first mined for commercial use in the 1880’s and was mined in one of the 17 opal fields (Erromanga). The reason why Australia has the majority of its opal and that it is in the middle area is because there used to be an inland sea over 100 million years ago. However this inland sea is only 1 piece of the puzzle many other events needed to occur for the opal to finally form. Here is a simplified version.
Side Note about opal formation: Some people believe that opal formation is due to a massive geological event that occurred in the opal bearing rock 70 million years ago (26 Million years ago for the QLD fields). This event caused a long period of acid rain which then leached silica from the rocks on a large scale – i.e. Asteroid impact on Earth, Massive Volcanic Activity. Other people believe that opal from as a result of hot springs)
Most opal has no colour except for black, gray, white or transparent. However if we are lucky and the silica solution is rich enough it starts to grow and form tiny silica spheres. They grow in a similar way to how a car battery works; the negative particles search for the positive particles. It has been proven that a raised tempature also helps in the formation of the spheres.Theses spheres could grow to the exact same size and if they settled down on one another then arrangement this would change the wavelength of light. The small spheres would create a blue play of could and it would go through all colour of the rainbow until we got red. Red being the rarest (and most valuable) of colours.
A couple of stories from a bygone era (quoted from Len Crams book)
1) “At the Quilpie field at a mine called the Red Show they discovered the second largest opal ever to be recorded. A huge red crystal pipe, over 8Ft in length and weighing 28 pounds (or 12 KG’s).”
2) With our industry there are some shady people … “Buyers often-filled miners with rum before asking them to display their opal on the pub veranda, Then kicked it into the dirt saying “What are you selling this rubbish for?” Broken spirited miner usually got little for his labor.
In the Australian outback there are different types of soil formation. In opal bearing areas we find that the top layer is permeable meaning that water can seep through it. What opal miners a looking for when they mine is small faults in the ground called slips, this is one of the ways that the water can move (at the point where the two earths meet).
The Winton formation is 900 x 400km stretch of land in Queensland where we find boulder opal - it is a massive area. The Good news about this fact is that the probability of there being lots of opal still in the ground is very high. The Challenge is that it's very expensive to unearth. An average operation with bulldozer and excavator runs to around $1000 per day in Diesel (not to mention breakdowns, setting up camp, buying equipment). In a nutshell, it costs a lot of money to mine opal and there is no guarantee to find any.
Sometimes people in the shop ask were the nearest opal mine is from Brisbane and we tell them lightning ridge which is about 10 hours drive. It takes 18 hours to get to our opal mine including 3 hours on an isolated dirt track.
Opal terminology & valuing has evolved over the decades. We have found that the easiest way to explain the many facets of opal is in the following way...
In the opal industry solid opal means that it is 100% natural and un-tempered. There are 3 types of solid opal, type 1, type 2 & type 3...
Type 1 - Classic Solid Opal. Is where the whole stone is either precious opal or a mixture of common opal (potch) and precious opal.
(Type1 opal type used to be the only opal called solid opal however, in the modern era often the word solid is referred to when what they are really after is an opal that is 100% natural (type 1,2, or 3 NOT a doublet, triplet or synthetic) therefore the industry has kept the word solid, however what is actually means for people in the opal industry is 100% natural - read on for the other two types of solid opal...)
Type 2 - Is what we call boulder opal. It is where the opal is a layer of opal naturally attached to the host rock underneath (usually ironstone). So it basically two stones ironstone and opal (a doublet can look the same but it is glued not natural and this effects the look and value dramatically).
Type 3. - Is what we call Matrix Opal. Matrix means to form inside of something else. So when we see a matrix opal we see on the surface of the stone o mixture of ironstone and opal.
In the old days only "type 1" opal used to be called 'solid opal' however what has happened is that the average consumer not familiar with the different type of opal (but aware of doublets and triplets) used to ask for only solid opals when after further investigation what they were really after was an opal that is 100% natural. So the industry adopted the term solid to now represent all the different types of natural opals (Classic solid opal, boulder opal & matrix opal) and classify them into the different types 1,2 & 3.
How are opals valued?
We look at these things, Brilliance, Colour and Pattern, Size and Shape. (Most important is the brilliance) then on a scale we work out a price per carat and then multiply the weigh to get a price. After doing this we will always reassess the item against our Wow! factor method. Valuating opals it is something build on experience; in seeing thousands of opals and more importantly selling thousands of opal - we know what people like, what they are willing to spend and how rare a particular opal may be.
The easiest way to think of the value of solid (natural) opals is to think of opals as artwork. Artwork is a good comparison because just like opals all artwork is unique. Some artwork is incredible and deeply moving and some is uninspiring and boring. Some artwork can sell for millions of dollars while some can't be given away. In a nutshell a quality opal will have a high 'Wow!' factor. A good way for understanding the Wow! factor is the following analogy. If someone was wearing a opal and had a one-on-one conversation with 100 different people. If a good portion of people commented on the item with-out any prompting then you would know that the item has a high Wow! factor if none of the 100 people mention it then you can be assured that it has a low Wow! factor. Opals with a very high Wow! factor are rear..
In short: As we mention at the bottom of all our invoices.."We value our opals according to our years of experience managing the balance between opal supply v's customer demand."
Doublets and triplets.
Taking the artwork analogy a little further. A mass-produced doublet is like comparing a copy of a painting to the original artwork. Would you pay the same price for an original piece of art as you would for an exact replica? I doubt it. So a doublet is like a copy of artwork. Looks great. But lacks that special something that an original piece of art possesses. Personally by biggest issue with doublets and triplets is that can loose their colour if they get wet over time (the glue fails and the opal gets cloudy).
Side note - Above I mentioned "mass-produced" doublets. This is where a very thin slither of opal is used. These retail around a 1/10 the price of what a solid opal of similar colour/brilliance/pattern would be. There are other doublets which have a thick amount of opal. These are closer to 1/4 the value. Personally we would not put doublets in gold.
Like all gemstones. There is also synthetic opals however thankfully for most synthetic opals it is easy to pick. The colour is very compact and the pattern has a regular feel to it (see pictures below). From our experience in Australia most businesses don't pass off synthetic opal as natural opal however I have seen many cases on eBay where the listing claims that the opal natural and from Australia when it is clearly synthetic. Below are a couple of cards showing the pattern and look of synthetic opal.
Some opals can crack
The good news is that if an opal is going to crack it will most likely do so with in the 1st 12 months of being exposed to the atmosphere. A rule that we have when it comes to opal and cracks in the shop is that if the opal has a crack and it's hard to see or does not effect the beauty, then we are more than comfortable to sell it, if it's silver (and we have silver jewellery up to the value of $2000). Why, because if it's in silver - we will have adjusted the price (according to our experience) taking in consideration the flaw- most likely the crack did not effect the beauty of the stone (otherwise we would have cut it out). If you wear it often then we know that it's brought joy to you life (otherwise you would not have worn it) and therefore a good investment,surface. and cracking...For more information on opal cracking please visit our shop website. For more information about opals that crack please visit our peace-of-mind page.