Gemstone: Opal – The Depths of Colour

“There are worlds in an opal.” – Terri Guillemets



The name opal derives from the Greek Opallos, meaning “to see a change (of colour).”  Opal is a formation of non-crystalline silica gel that seeped into crevices in the sedimentary strata.



Opals range in colour from milky white to black with flashes of yellow, orange, green, red, and blue. The pattern and arrangement of the colour which displayed in an opal can take on many beautiful forms. The movement of colour across the face of a stone is known as the ‘play of colour’.

The colour in an opal is caused by diffraction of light. Much like a prism, which can refract white light and produce a rainbow effect. Opals diffract the white light which is coming from above, displaying the beautiful aray of colours.



Modern Birthstone – October

Anniversary – 14th

Birthstone – Libra



Around 95 percent of the world’s supply of white precious opals are mined “down under”. Famous deposits in New South Wales are at Lightning Ridge and White Cliffs. In South Australia at Coober Pedy and Andamooka. Various deposits are also found in Queensland.

Other deposits are found in Brazil, Ethiopia, Guatemala, Honduras, Indonesia, Japan, Mexico, Russia and the United States.



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Opals measure a 5.5-6 on the Mohs hardness scale of hardness. The MOHS Scale starts with talc at 1 (being the softest mineral), and ends with diamond at 10 (being the hardest mineral). Opals are about the same hardness as glass.



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Opals are believed to have healing properties. Opals are said to be effective in curing eye infections and enhancing one’s creativity. As well as calming nerves and strengthening memory.

The ‘Andamooka Desert Flame’, is the largest opal ever brought to the light of day. Weighing 6,843 kilograms. (Whoa!!!)

Opal as a birthstone symbolises purity, innocence and hope.

‘Big Ben’ is a white precious opal of over 800 grams. More than 4000 carats, which was found at Lightning Ridge, Australia.

Black opals are the most rare, whereas white and greens are the most common.


Click to discover more interesting facts about Peridot or Sapphire gemstones.

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