A Guide to Opals
Play of Colour • One of a Kind • October Birthstone
Opals are unlike any other gemstone. Their captivating play of colour, where vibrant hues shift and shimmer within a single stone, makes each one entirely unique. No two opals are ever the same, which is part of what makes them so special. As the birthstone for October, opals are associated with optimism, confidence and good fortune. They do require a little more care than harder gemstones, with a Mohs hardness of 5 to 6.5 and a water content of up to 30%, but handled and stored properly, they reward their wearers with a beauty that is genuinely unmatched.
The Different Types of Opal
Opals come in a wide variety of types, each with its own character, origin and value. Understanding the differences helps you choose the right stone for your jewellery and your budget.
Black Opal
Body Tone Dark or black base Value The most valuable type of opal Origin Primarily Lightning Ridge, Australia Character Vivid, bright play of colour that stands out dramatically against the dark background, producing some of the most striking gemstones in the world.
White Opal
Body Tone Light or white base Value More accessible than black opal Origin Coober Pedy, Australia Character A softer, more subdued play of colour. Often referred to as milky opal. A beautiful and wearable choice for everyday fine jewellery.
Boulder Opal
Body Tone Dark, with natural ironstone host rock retained Value High, particularly with vivid colour Origin Queensland, Australia Character Unique natural patterns with strong colour contrast against the host rock. Each stone is genuinely one of a kind.
Fire Opal
Body Tone Transparent to translucent, red, orange or yellow Value Depends on clarity and play of colour Origin Mexico Character Prized for its warm, fiery body tone. May or may not exhibit play of colour. A bold and distinctive choice.
Common Opal
Body Tone Opaque, no play of colour Value More affordable Character Also known as potch, common opal is solid in colour with no iridescence. Sometimes used in carvings or more accessible jewellery pieces.
Doublet Opal
Composition Thin slice of precious opal bonded to a dark backing Value A more affordable alternative to solid black opal Character Mimics the appearance of black opal and provides vibrant colour at a lower price point. Should not be submerged in water as the adhesive can deteriorate over time.
What Determines the Price of an Opal?
Opal pricing is shaped by several factors working together. Understanding what to look for helps you make a confident and informed choice.
1
Type and Body Tone
The type of opal and its body tone are the primary drivers of value. Black opals with dark tones are generally the most highly prized, while white and common opals sit at the more accessible end of the market.
2
Colour and Pattern
Brightness, range of colours and the distinctiveness of the pattern are major value factors. Rare patterns such as harlequin or rolling flash are the most sought after. More vivid and varied combinations command higher prices.
3
Transparency and Clarity
Transparent or semi-transparent opals such as crystal opals can be especially valuable, particularly when they exhibit vibrant play of colour with minimal inclusions or imperfections.
4
Size, Shape and Cut
Larger opals are rarer and typically more valuable. Well-cut stones with appealing shapes that enhance and showcase their colour are preferred. Poor shape or an unflattering cut can significantly reduce a stone's appeal and value.
Famous Opals That Captivated the World
Throughout history, certain opals have achieved legendary status, celebrated for their extraordinary size, colour and the stories they carry.
The Aurora Australis
Discovered in 1938 at Lightning Ridge, New South Wales, the Aurora Australis weighs approximately 180 carats and is widely considered the most valuable black opal ever found. Its vivid harlequin pattern, with dominant red, green and blue hues against a deep black background, has never been surpassed.
The Olympic Australis
Found in 1956 at the Eight Mile opal field in Coober Pedy, the Olympic Australis weighs an extraordinary 17,000 carats, approximately 3.4 kilograms, with 99% gem quality opal throughout. It is recognised as the largest and most valuable opal ever discovered.
The Fire of Australia
Discovered in 1946 at the Eight Mile field in Coober Pedy, the Fire of Australia weighs approximately 5,000 carats and is celebrated for its brilliant flashes of red and orange. Its two polished faces reveal a kaleidoscope of colour. It is now housed in the South Australian Museum.
The Andamooka Opal
Found in 1949 at Andamooka, South Australia, this 203-carat stone is also known as the Queen's Opal. It was presented to Queen Elizabeth II during her 1954 visit to South Australia, cementing its place in both gemstone and royal history.
Quick Facts
Birthstone October (with Tourmaline)
Anniversary 14th Year
Hardness 5 to 6.5 Mohs
Notable Sources Australia, Mexico, Ethiopia
Special Feature Play of Colour
Rarest Variety Black Opal
Why Choose Opal Jewellery?
Opal jewellery offers a beauty unlike any other gemstone. The mesmerising play of colour, where vibrant hues shift and shimmer within a single stone, gives every piece a sense of life and movement that is entirely its own.
Each opal is unique, which means every piece of jewellery made with one is personal in a way that no other stone can replicate. From the rare intensity of a black opal to the warm fire of a Mexican variety, there is an opal to suit every taste and every occasion.
Beyond their beauty, opals hold real symbolic meaning. As the birthstone for October, they are associated with optimism, confidence and good fortune, making them a thoughtful and meaningful gift as well as a stunning addition to any jewellery collection.
Discover Our Opal Collection
At Cheshires, each opal is hand-selected for its colour, character and quality. Visit us in store to view our curated selection, or book a personal appointment with our gemstone specialists.
