While opals come in varying shapes and sizes, and they are generally quite resistant or wear and tear, being a natural opal does have its disadvantages. One big disadvantage to natural opal is water. There are types of natural opal that disintegrate when water leaches out of it.
There have also been instances wherein natural opals crack when water disappears from the opal. Synthetic opal rough do not have this problem as they are made from essentially the same material as the real opal, silica, and instead of water being the vehicle that carries that silica to form opal, another medium is used for synthetic opal rough.
Different Types of Synthetic Opal Rough
There are a lot of types of synthetic opal rough that can be purchased from the internet nowadays. For high value jewelries, the Gilson process is used to create the most natural looking synthetic opal rough. For cosmetic or low value jewelries, however, the Gilson process would be way too expensive to be used.
A type of polymer is used to bind the silica to form these synthetic opal rough that you can buy anywhere. This polymer can be made to match any shade of color, and any varying opacity to match any requirement that you need.
The synthetic opal rough that you can find on the internet are polymer impregnated. This means that the ‘glue’ that was used to bind the silica together is a type of polymer, or what can be called a type of super glue, in layman’s term to slowly bind the silica into the synthetic opal rough shape that you can see.
The overall looks of synthetic opal rough is that is has an unnaturally even texture about it. This texturing that you can see on the outside of the synthetic opal rough makes it known as manufactured. You will not be able to find a standard type of texturing in natural opals, but opals of high value will not be found in size of larger than 1 or 2 carats, either, unlike synthetic opal that you can buy in 1000 gram or even beyond 4 or 5 kg shipments.
The use of these types of synthetic opal rough would depend on what type of opal you need. For cosmetic jewelries that anyone can buy, a 2 or 3 kilogram block of synthetic opal rough would be enough to make thousands of opals in various designs, and this will lower the cost of making your intended type of jewelry.
If, on the other hand, you intend to buy an alternative to high priced opal jewelry but want something that looks natural, then the Gilson process used for synthetic opal rough is much better suited to the task.
Rather than just using a polymer to bond the silica into place, a jewelry quality synthetic opal rough is grown inside a lab. Much like the way the natural opal was grown, but in this process, the silica is introduced rather regularly and the way the opal is grown is by artificially putting weight to it as it would on a centrifuge.
You have known that synthetic opal do not contain water at all, but unfortunately a liquid is still needed to transfer and support the silica in its growth. Most labs who grow synthetic opal use a nod water base liquid that easily disappears or vaporizes when needed. Most of the time they use ethanol as the liquid carrier when growing synthetic opal rough.
So after the synthetic opal rough has been grown, it needs to be dried. Unfortunately, you need to dry the opal in such a way that the silica does not crack but at the same time allowing the liquid to escape. The people at the lab then use what is termed as an auto clave, or a very hot oven that they can control the temperature exactly, in order to make the ethanol evaporate completely and dry the newly formed synthetic opal.
It is only a matter of examining for flaws, cutting and polishing to bring out the luster and the brilliance of the newly formed synthetic opal.
Most of the other types of processes that is used to make synthetic opal is based on this process, the only thing that is difference would be the liquid that is used and how to accelerate the deposition of the silica into the seed. Other types of processes use other ways of making that silica seed grow and other lab use chemical deposition to put consistently put layer upon layer of silica over the seed and in the process, create that dazzling array of play of light and brilliance and fire that can only be seen with natural, jewelry quality opal and synthetic opal rough that are created in the same way that natural opals were created.
Most shops do advertise synthetic opals as synthetic, since they would sell it at bulk, but even jewelers who sell synthetic opals normally say if the opal that they are selling are synthetic or not.