A Guide to Opals

Opals are unique and beautiful gemstones, admired for their colourful display, which can show many different shades in just one stone. They contain up to 30% water, so over time they can dry out and crack, especially if kept in warm conditions. Opals are also quite soft, with a hardness of 5 to 6.5 on the Mohs scale, so they need to be handled gently and stored properly. As the birthstone for October, opals are associated with optimism and confidence, and are believed to bring good luck and happiness to those born in that month.

Different types of opal:

Black Opal
Body tone: Dark or black base
Value: The most valuable type
Origin: Primarily Lightning Ridge, Australia
Features: Bright, vivid play-of-colour stands out dramatically against the dark background
White Opal (also called Milky Opal)
Body tone: Light or white base
Value: Less valuable than black opal
Origin: Coober Pedy, Australia
Features: Softer play-of-colour; often more subdued
Boulder Opal
Body tone: Usually dark, with natural host rock (ironstone) remaining part of the gem
Value: High, especially when the colour is bright
Origin: Queensland, Australia
Features: Unique natural patterns, with strong colour contrast against the host rock
Fire Opal
Body tone: Transparent to translucent, typically with a red, orange, or yellow base
Value: Depends on clarity and whether it displays play-of-colour
Origin: Mexico
Features: May or may not exhibit play-of-colour; prized for its fiery body tone
Common Opal (or Potch)
Body tone: Opaque, with no play-of-colour
Value: Low
Features: Solid in colour; sometimes used in carvings or low-cost jewellery
Doublet Opal
Composition: A thin slice of precious opal bonded to a dark backing (often ironstone or black potch)
Value: A more affordable alternative to solid black opal
Features: Mimics the appearance of black opal; not considered natural or whole, but provides vibrant colour at lower cost
Note: Should not be submerged in water, as the adhesive can deteriorate

What determines the price of an opal?

Opal Type and Body Tone:
The type of opal (e.g., black, white, boulder, crystal) and its body tone (dark versus light) greatly influence value; black opals with dark tones are generally the most highly prized.
Colour Quality and Pattern:
Brightness, range of colours, and the distinctiveness of the colour pattern (such as harlequin or pinfire) are major value factors; more vivid and rare combinations tend to command higher prices.
Transparency and Clarity:
Transparent or semi-transparent opals (like crystal opals) can be especially valuable, particularly if they exhibit vibrant play-of-colour and minimal inclusions.
Size, Shape, and Cut:
Larger opals are rarer and typically more valuable, and well-cut stones with appealing shapes that enhance their colour are preferred over flawed or poorly shaped examples.

Famous opals that captivated the world

Aurora Australis

Discovered: 1938, Lightning Ridge, New South Wales, Australia
Weight: Approximately 180 carats
Notable for: Vivid harlequin pattern with dominant red, green, and blue hues on a black background
Claim to Fame: Considered the most valuable black opal ever found

Olympic Australis

Discovered: 1956, 'Eight Mile' opal field, Coober Pedy, South Australia
Weight: 17,000 carats (approximately 3.4 kg)
Notable for: 99% gem-quality opal with even colour distribution
Claim to Fame: Recognised as the largest and most valuable opal ever found

Fire of Australia

Discovered: 1946, Eight Mile field, Coober Pedy, South Australia
Weight: 998 grams (approximately 5,000 carats)
Notable for: Brilliant flashes of red and orange; two polished faces revealing a kaleidoscope of colours
Claim to Fame: One of the world's finest uncut opals, now housed in the South Australian Museum

Andamooka Opal (Queen’s Opal)

Discovered: 1949, Andamooka, South Australia
Weight: 203 carats
Notable for: Brilliant colours and historical significance
Claim to Fame: Presented to Queen Elizabeth II during her 1954 visit to South Australia

Why choose opal jewellery?

Opal jewellery offers a truly distinctive and captivating beauty unlike any other gemstone. Known for their mesmerising play-of-colour, where vibrant hues shift and shimmer in a single stone, opals provide a one-of-a-kind aesthetic appeal. Each opal is unique, making every piece of jewellery special and personal.

There are several varieties of opal to suit different tastes and budgets. From the rare and highly valued black opals of Lightning Ridge to the vivid, ironstone-backed boulder opals of Queensland, and the fiery, translucent Mexican fire opals, each type offers its own charm. More affordable options like white opals, doublets, and common opals still showcase beautiful colouration and can make excellent, budget-friendly choices.

Beyond beauty, opals hold symbolic value. As the birthstone for October, they are associated with optimism, confidence, and good fortune. Many believe opals bring happiness to those who wear them, making them a thoughtful and meaningful gift.

While opals are softer than many other gemstones, with proper care and storage, they can be enjoyed for generations. Their rarity, historical significance which is highlighted by famous stones like the Aurora Australis and Fire of Australia and natural beauty make opal jewellery a timeless and emotionally rich investment.