Project Description

OPAL

Opal jewellery available to purchase

Opal is the birthstone for October, the gem for zodiac sign Libra and the 24th wedding anniversary gemstone.

Precious opal is one of the most unique and beautiful gems.  Unlike most gemstones, Opal is amorphous which means it does not have a defined crystalline structure and occurs in many shapes and colours.

The play of colour you see in opal is due to millions of tiny silica spheres in a close-packed lattice.  These spheres refract light and cause the beautiful spectral colours you see in an opal. The regularity of the sizes and the packing of these spheres determines the quality of precious opal.

It is estimated that over 90% of the world’s opal comes from Australia.  Other popular countries that mine opals include Ethiopia, Brazil, Mexico, Indonesia, the Czech Republic and the USA.

Opal is formed in two ways.  Australian Opal is sedimentary in nature and is formed when rainwater seeps down into crevasses in the rock.  As the water evaporates, the silica that is left behind dries out and over millions of years, this silica hardens into precious opal. Ethiopian Opal, on the other hand, is volcanic in origin which gives it different properties to Australian opal.

The water content of opal can range from 3% to 21% but is normally between 6% and 10%.

Australian Opal range from the most commonly white or ‘milky’ opals found in Coober Pedy in Queensland to the rare black opals of Lightning Ridge in New South Wales and boulder and matrix Opal in South Australia and Queensland. Boulder opal has a layer of solid brown ironstone left on the back of the stone while Matrix Opal consists of very thin seams or spots of precious opal intermixed with the dark ironstone or light sandstone host stone.

Generally, solid opals with a black or dark body tone are more valuable than those with a white, light, or crystal body tone because a stone with a darker body tone tends to display colours more vibrantly.

Australian opal formed in narrow fissures can produce very thin opals. Opals too thin to produce a “solid” as usually made into doublets or triplets.  An opal doublet consists of a thin layer of precious opal, backed by a layer of dark material which emphasizes the play of colour, producing a similar effect to black or boulder opal at a fraction of the price.  An opal triplet is similar to a doublet but has a third layer, a domed cap of clear quartz or plastic on the top. The cap takes a high polish and acts as a protective layer for the opal. The top layer also acts as a magnifier, to emphasize the play of colour of the opal beneath, which is often of lower quality. Triplet opals, therefore, have a more artificial appearance and are not classed as precious opal. At Faller, we only sell solid opal which means stones consisting wholly of precious opal.

Fire opal commonly from Mexico is a transparent to translucent opal, with warm body colours of yellow to orange to red. It is sometimes known as jelly opal. Although it does not usually show any play of colour, occasionally a stone will exhibit bright green flashes. It has a higher water content than other opals.

At Faller, we love Ethiopian opal as it’s affordable and it shows an amazing play of colour. Ethiopian is more readily available in a wider variety of colours, in larger sizes and at lower prices than Australian opal. The price per carat of Ethiopian opal is based on the intensity, variety and patterns of colour.

Extra care needs to be taken as opal can be scratched relatively easily and any hard knocks can cause the opal to crack.  It is not recommended for rings that are worn daily but it is fine for use as pendants, earrings and brooches. Always remove any opal jewellery prior to playing sports, exercising, swimming or doing any household chores or gardening.

As opal has relatively high water content, it is sensitive to heat. In particular, never leave Australian opal jewellery on a sunny window sill were drying out can cause hairline cracks known as crazing. Always avoid using any chemicals, toothpaste or abrasives when cleaning your opal jewellery.  Clean with warm soapy water and a soft child’s toothbrush to remove build up under the stone.  Rinse well to remove any residue and dry with a soft lint-free cloth. Australian opal won’t react when soaked in water.

Care should be taken when wearing or storing any opal around other gems and jewellery.  Ideally, store them in a sealed plastic bag with a damp cloth in case of drying out.  To restore moisture in opal, rub a finger gently over the surface to contribute natural skin oil.  Opals can also be rubbed with a bit of baby or mineral oil on a cotton swab.

When cleaning a doublet opal or triplet opal, do not immerse it in soapy water which may loosen the glue and separate the pieces. Instead, put a small amount of solution on the microfiber cloth and gently clean the opal with it.

If Ethiopian opals come in contact with water, they will absorb it like a sponge. This characteristic is known as hydrophane.  If placed in water, the material will become glass clear, and when removed, it will get milky, and after several days, the material will return to its original beauty. What this means is you shouldn’t swim with it, while washing your hands will have little effect. Being absorbent, chemicals including hair products, dyes, oils and lotions should be avoided. Ethiopian opal once cut is highly stable.  As the stones can be cut into thicker shapes it is more durable, resisting breakage better than all another opal including Australian opal.

Gemstone Guide