Opal, the play of all colours

Setting opals well in gold is a delicate art, it takes time to learn to do it well.

Opals may have an irregular shape and a curved back, adding additional complexity to the setting work.
Setting opals into the jewellery work is done under the microscope through a careful process, that in some settings may take more then a good few hours to complete.
Over the years, I had to come up with my own ways of setting these fragile and beautiful stones.blackOpal

Opals here are usually set in thick high-karat gold,  Often setting is a process of slowly hammering the gold bezel over the opal until it is fully rested on the edges of the stone, then it is burnished with a studio made steel or bronze or brass burnishers depending on the particular need and the hardness of the Opal, to a fine finish.
(Most of the opal samples on this page, were cut and polished by me in-studio, with an exception marked with *.)

preciousOpalMost opals suitable to be set in jewellery originate in Australia. It is noted where stones from other location are shown. There are many kinds of opals, and different types of ‘mother-rocks’ in which the opal veins form. Opals are often referred to as either Precious or Common.

Precious, and high to mid range opals.
The term Precious Opal refers to high to top quality stones. Its use, ‘to my understanding’ is flexible and generalizing, and may depend on one’s perspective.

Black Opal has a semi-opaque to translucent black or near black body and is usually quite hard and durable. Precious black opals are among the most beautiful and expensive in the opal family. The black body brings out the opal’s Fire in the most vivid way.

Yowah Nut. Up to now I worked only once with this rare and expensive type of opal. At this time I haven’t got a photo to post here. The gem is like its name, a nut shaped brown rock (probably Iron-stone), with a nucleus of fantastically bright opal.

Fossil Opal. Sometimes the opal which is a form of silica gel replaces organic material like bone wood or shells, these opals often have a very bright multi-coloured Fire.
Shell material because of its shape, is often very difficult to cut into a gemstone.

White Opal has Fire or colour within a white or near white background.

Dark [or Grey] Opals. Many shades of grey and blueish grey exist between the black and the white bodies. Some of these stones may have fantastic Fires.

Crystal Opal. These stones have a clear transparent to translucent body. Crystal opals [at least the stones I cut] looks much like amber if a light source is placed behind it. Often, setting the stone into a darkened setting is required in order to show well the Fire in this enchanting and often durable type of opal. Fire is usually in shades of blue with some green.

Boulder Opal is an ironstone rock containing predominantly thin veins, layers or pockets of opal crystallized gel. Fire is often green and usually bright. Red Fire is uncommon, and adds to the cost of a stone.

nformation and Terms – Looking at opals.

Fire. Used with a capital F the term refers to the vivid play of colours in opals.

Hardness. Different kinds of opals have various degrees of hardness, ranging from 5.5 to 6.5. in the Mohs scale. The harder the opal, the more durable it is. Harder stones will also hold a better polish.

Colours of the opal’s Fire. Practically all colours, deeply saturated, are found in opals. The red colour being the most valuable and rare; orange, yellow, and purple come next in the order of rarity of appearance, while blue and green are the most commonly occurring colours.

Brightness of Fire,
and its direction, are very significant.
When viewed from the top (main viewing direction), bad direction will result in a grey appearance. A dull Fire is just that, and makes for a relatively unattractive stone.

Pattern refers to the arrangement of the Fire. A random spread of colours is termed Floral.
A pattern which (although beautiful), is the least valuable and most readily occurring.

Special patterns include Broad Flash: where a large area of Fire flashes intensely at certain angles. A Rolling Flash: where the flash rolls along the stone as you gently rotate it.
Pinfire is an interesting pattern showing many small dots, like stars in the night sky.
These stones may look unreal… like a candy – even fake, but its Mother Nature’s creation.

Patterns that are more valuable include Flagstone – well defined patches of colour next to each other, Straw, Chinese Writing, and Ribbon.
The fanciest and rarest pattern is called Harlequin, a tile like arrangement of different colours of bright Fire.

Shape. Most opals are cut as cabochons; the round form is most suitable in enhancing the play of Fire. Shapes are often oval, ranging from high domes to a full flat surface. The choice in cutting and shaping opals has to do with the shape of the rough and the direction of the Fire.
If the Fire’s orientation is other then top view. A high dome (or in larger stones, curving) could be the answer for cutting a pretty stone. Often opals are cut to an asymmetrical or amorphous shape.
This is done at times for artistic purpose, but mostly in order to preserve and best show as much fire as possible. Setting techniques must be considered in shaping an amorphous stone.

Curving opals serves a few different purposes. Foremost is artistic expression. Yet often curving is used as a beautiful way of removing flaws, like dull unattractive areas or sandpits. Curving may allows the exposures of different layers of Fire, otherwise obscured in a regular cab shaped cutting (cab is short for cabochon). Limitations on curving opals are the size of the rotary diamond tools, the rounding of edges by the polishing buffs, and strength and durability considerations.

Body Colour is the shade of mother rock. Often in high quality opals, The Fire dominate the visible area of the stone, showing very little or no body colour. Dark body colour gives better background by enhancing the opals Fire.
Solid – an opal is said to be solid when its body is thick enough to withstand reasonable wear while set in jewellery.

Nearly Solid refers to a stone which may have a certain small area that needs strengthening (done by cementing a piece of poach or filling a backside small cavity with powdered poach mixed with epoxy cement).

Semi Solid is the same but with a larger added piece. In both Nearly Solid and Semi Solid the treatments has to do only with making the stone stronger and more durable, they do not change its appearance.

Solid with Backing – sometimes a transparent Crystal Opal will need a dark backing (like the paint in the back of a mirror), this is done by cementing a slice of black Poach to the back. The treatment brings out the full Fire in the transparent or translucent Crystal Opal.

The next category in Solidity is Doublets, discussed farther alongthe page, under: Doublets Triplets Synthetics and Imitations.
Occurrence: Some 95% of opals are of Australian origin. A different type of fairly well known opals comes from Mexico, and some high quality stones comes from the north of Brazil. Opals are found in the USA, in Idaho and Nevada, yet good quality material from these locations is rare.
There is some material arriving from Africa: I’ve read of stones from Ethiopia and Mali. It is possible other locations exist, which I am not aware of at this time.

Common Opals
The demarcation line between Semi Precious and Common Opals is not sharp to my understanding, At times it may depends on one’s interpretation or interest…
All types of Precious Opal in their respective low qualities are said to be Common Opals.

Hydrophane Opal is very porous. Immersed, it will absorb water and become very bright with colourful Fire. The Fire, or most of it, only lasts a few days and the stone dries up to a dull brown rock. Being very soft it will not polish well. This type of opal (found, I think, mostly in the USA) is not suitable for use in jewellery! (a lesson I learned years ago after making two rings with stones I had to later on replace!)

Matrix Opal is made of lots of tiny opal veins or dots spreads like sparkles throughout the brown mother rock, usually ironstone. A similar occurrence in sandstone, is called (according to my reading) Mass Opal.
Found concentrated enough within the mother rock, these little opals make for a very attractive stone. Sometime Matrix stones are treated to blacken the mother rock, far intensifying the appearance of the opal sparkles.

Fire Opal is the popular name for stones mostly found in Mexico that possesses an attractive orange body colour but have no or very little Fire. These stones are often faceted.

Poach Opal is an opaque to translucent to nearly transparent opal rock which has no fire. It ranges in colour from black to white through all grays and blue-grey.

Wearing, Energy, and Caring for opal jewellery .
Opals are wonderful stones to wear in jewellery. Their energies are a bit unlike most other gemstones. I will be very careful in saying what is what, avoiding the repetition of information available in books and on the net. Please feel the stone first. No need necessarily, to try to define what you feel. Perhaps later on read, if you are interested to know more, there is a lot of interesting information available through different sources. One thing I’ll mention though; it is said of opals that they are like subtle energy batteries, carrying different flavours of energy. Like the opal’s Fire with its tantalizing play of colours, shifting and changing as your eyes move. Allow your opal jewellery to be charged with Love and with Light.
Find the way to ‘do’ it, that you feel is right for you.
Cleaning and Caring. This is a truly important paragraph for everyone wearing opals. How to take care of these sensitive stones: Opals are very vulnerable to heat. A good rule of thumb would be the heat your body can take! – opal would safely withstand and no more. Yet avoid sudden intense temperatures change. Opals are sensitive to most chemicals. Remove your opal ring before doing rough work, anything from dishwashing to fixing your car!
Opals will be ok in contact with vegetable oils, ethanol (edible alcohol) and even a gentle touch with acetone, Mild soaps and most body creams will not harm gem quality opal. It is always a good idea to rinse well in fresh water after contact with any substance.
Avoid letting opals contact petroleum based oils (such as car oil) and just about all other toxic and staining chemicals.

Opals are also fragile, and may brake if accidentally dropped on hard floor or hit with a hard object. Harder stones, as well as various abrasives and carbide tools will scratch it; even hard steel may leave a mark on soft spots.

Opals like best fresh water. If dirty, opal jewellery can be safely and easily cleansed with a bit of gentle dish-washing liquid mixed with water and applied with a soft tooth-brush (these battery operated brushes are great for the hard to reach areas at the back of some jewellery). After cleansing, rinse well with fresh water. NEVER Immerse opals in a jeweller’s ultra-sonic cleanser! It is best to avoid taking opals to swimming pools. Some pools are not so heavily chlorinated, but still do not experiment too often. If you have, please rinse the opal well in fresh water. Opals vary in porosity so some are more susceptible than others are to chemical damage. (Chlorine, over time will also damage gold) Definitely do not let opals into public hot tubs where, under the influence of heat, chlorine is more reactive and damaging to jewellery. Completely resistant to chlorine are gemstones like rubies and diamonds, and platinum. Sand is hard enough to scratch opals (and gold) therefore, it is better not to bring opals to the beach! I’m not sure about the salty water, but the ocean Gods often take fancy to pretty jewellery!
In time, it is normal to observe some fine scratch marks and some loss of polish that gradually show, especially on opals in rings one wears everyday.
It is a normal to re-polish these stones once every few years. (I do this re-polishing for the opals in my jewellery work without charge.) Problems may arise if a stone has been badly abused with very deep scratch marks. which reminds me of a Black Opal ring brought to me a while back for repair, it was lost and found on a dirt road where cars drove over it many times. (Remarkably the stone did not break or crack even though the gold ring was flattened like a sandwich!)

Some opals have a very thin layer of Fire. In these stones re-polishing is difficult, a light polish may be possible to restore the shine but deeper scratches will unfortunately, remain…

Doublets Triplets Synthetics and Imitations.
Opal Doublets are widely used in Jewellery. Often a beautiful opal would be too thin and therefore not strong enough to withstand wear in jewellery. It is strengthened by cementing a slice of poach to its back. More commercial is the practice of cutting very thin slices and cementing in the same way to poach; these are the commonly found Doublets.

Triplets are made by sandwiching with clear cement a very thin slice of opal between a dark poach back and a clear crystal top (or other material). This result in a durable construction that is well resistant to scratches.

Synthetics – The definition for synthetics is that of a man made material, created with exactly the same mineral composition as its corresponding natural stone.
I work only with natural stones, and synthetics are pretty much outside my field of knowledge. Therefore, I cannot really comment on this subject. There is plenty of information on the net for the interested mind.
In gemstones with a crystalline formation like diamonds, sapphires and others, synthetics will have the same physical properties as the natural stones – hardness, density, refraction index and so on… In opal, I am not sure if that is so, opals vary quite a lot in their physical properties.

Imitations are simply look-alikes and can be made of any material (usually glass or some polymer). They are sold everywhere and will not fool the experienced eye. Gem imitations have their place in ‘custom jewellery’ as long as they are disclosed for what they are.

Writing about opals: I would like to add here my special thanks to Arpana (Jay Lennon) who allowed me, over the years, to dig into his buckets of rough, put aside some of his best rocks and all the while learn a lot about opals.

Intended for people coming from outside the jewellery and gem circles, certain more detailed or specialized information was not included. I hope this article may be of value to those who are interested in opal jewellery and in my work.

The information in this page was based on personal experience, on talks with people from within the opal trade, and some reading. I am no expert on opals and have no certified qualification on the subject! Professionals and people in the opal trade,will find more established sources of information on the net.