Oct 5, 2022

25 Things You Wish You Knew About Opals

It's time to dive into the October birthstone and talk about everything you ever wanted to know about the opal gemstone .

History Lesson So when was the opal gemstone first discovered? There exists artifacts containing this gorgeous gemstone dating back as far as 4000 B.C., uncovered by anthropologist Louis Leakey in a cave located in Kenya. Opal has certainly been described and used further along in history by the Ancient Greek & Roman civilizations, but this finding of artifacts is a significant point in history where we can place opal being used. In gemmology terms, in reference to the most important source of opals today, the discovery of opals in Australia was made by the geologist Johannes Menge in 1849. Gemmology as a distinct science would not exist yet until 1908, when Samuel Barnett proposed setting up examinations and the teaching of gemmology. The name 'opal' is actually derived from the Latin 'Opalus' and Greek 'Opallius', both meaning 'to perceive a colour change' which is very apt for this vibrant gemstone. Opal Lore

“Some opali carry such a play within them that they equal the deepest and richest colors of painters. Others…simulate the flaming fire of burning sulphur and even the bright blaze of burning oil.” - Gaius Plinius Secundus (AD 23/24 – 79) The opal gemstone is the recognised birthstone for October, and it is brimming with superstition and magic. A novel written in the 1800s sparked this worry of it being seen as 'unlucky' to wear opals unless you were born in the month of October, especially darker toned opals, although by Queen Victoria's reign in the mid to latter half of the 19th century, the Opal was back in fashion. Queen Victoria loved opals, and wore them throughout her reign, famously even receiving Queen Charlotte's opal cabochon and pearl ring from her Aunt Princess Mary in 1849. Prince Albert gifted their daughters with opals on their wedding days, promoting a more positive view of this spectacular gemstone.

Image source; Royal Collection Trust. Queen Charlotte's Opal Finger Ring. Opal is credited by a mix of culture to be associated with supernatural origins and powers. European legends see the gem a symbol of hope, purity and honesty. Falling from the cosmos in lightning storms, as told by Arabic legends, or the belief that opals lend their wearers the gift of prophecy and guarded them from disease, as believed by the Ancient Greeks.

Gemmology So what are opals made from, and how do they form? Opals are a hydrated amorphous form composed of silicia, which consists of multiple tiny spheres all arranged in a regular pattern with water in-between the spheres . The opals form when silica rich water seeps into deep cracks within the Earth's crust at low temperatures, and then some 5-6 million later under the right conditions, et voila opal is formed. Due to opals having amorphous properties, the opal gemstone is classed as a minerloid rather than a mineral. The silica spheres act as a prism to the light entering the opal, and create the fabulous play of colour for which opal is so prized. The play of colour can be more subtle or extremely intense, dependant on the size of the spheres and the spaces inbetween them.

Because opals are so water rich, they are very susceptible to drying out and cracking; It is not uncommon to see incorrectly stored opals begin to show signs of this, and this is also why a lot of gemstone suppliers believe they need to ship their loose opals in water, but this is generally seen in the industry as not necessary and not recommended. Care instructions recommend environments that are not too dry, and in temperatures that are not too high. Opals are also a relatively softer gemstone, sitting at a 6 on the MoHs scale of hardness, a scale that places gemstones relative to each other in their ability to resist abrasion. For reference a diamond sits at a 10 and is the hardest material on the scale. The ranking of 6 means opals can be scratched and scuffed easily, and this is also why you will see them fashioned most frequently as a cabochon, a style that offers more protection than sharp faceted sides and angles.

Types Of Opal Opal is sorted into two broad classes, known as common opal and precious opal. It is found all around the world, but the most important source of opal is found in Australia. So what is the difference between these two groups of opal? The opal you see that displays the colour flashes and play of colour is precious opal, whereas common opal is visually distinct from this group and does not display any play of colour, but does still exist in a range of colours. Within this category of common opal, the groups can be split and defined further into ;

Agate Opal
Dendritic Opal
Cats-eye Opal
Wood Opal

Image Source ; Wikipedia ( Wood Opal ) - Image showing petrified wood which has been replaced by opal and now carries an opalescent sheen Famous Opals

The Andamooka Opal is arguably one of the most famous opals, also referred to as 'The Queen's Opal' due to its connection to Queen Elizabeth II. The stone is a 203 carat opal found in 1949 in the Andamooka opal field of Australia. The opal was cut and set into a choker and gifted to Queen Elizabeth II in 1954 during her first state trip to Australia, the piece of jewellery is considered a significant jewel within the Queen's state jewellery collection.

Image source; Pinterest. The Andamooka Opal set into the choker necklace gifted to Queen Elizabeth II

Queen Alexandra inherited an opal tiara (The Oriental Circlet Tiara) from Queen Victoria when she died in 1901, which featured 11 precious opals. The tiara was designed by Prince Albert himself to gift to Queen Victoria, opals were said to be his favourite stone so a lot of Queen Victoria's jewellery collection is said to include opal pieces. Queen Alexandra firmly believed that opals brought misfortune so she had them changed to rubies before she began wearing the tiara. The crown still remains within the The Royal Collection with the intention of being worn by all future queens, and still houses the rubies.

Image source; Left - royalwatcherblog. Queen Victoria wearing the Oriental Circlet Tiara.

Eric the Pilosaur is one of the world's most complete opalised skeletons. Found by an opal miner in an Australian opal mine in 1987, this carnivorous marine reptile's bones had been opalised thanks to the area of land it was buried in to have an exceptional level of opal mineral in the ground. This resulted in the bones having a beautiful shine to them. The miner who found Eric sold him off to a businessman to begin the reconstruction of the skeleton, but due to huge financial difficulty, he considered breaking it apart to be sold off for jewellery. The Australian Museum purchased the skeleton in 1993 where it is now on display and is considered a national treasure to the country.