White Opal & Crystal Opal
Coober Pedy white opal and Australian crystal opal varieties - characteristics, quality grades, and market position.
Introduction
Coober Pedy, South Australia — whose name derives from the Aboriginal phrase
"kupa piti" (white man's hole) — was first worked for opal in 1915 and is now the
largest opal mining area in the world. [1] Underground
shaft mining dominates because the desert climate makes surface work impractical;
miners historically lived in subterranean "dugout" homes excavated from the
Cretaceous sandstone.
White opal occupies the N7–N9 body-tone range; the pale background limits contrast,
making brightness the critical value factor. Vivid full-spectrum broadflash with red
fire on a white opal rivals some black opal in appeal. Crystal opal — transparent
to semi-transparent — displays play-of-colour with a depth that white opal cannot
match.
Treatment distinction is commercially important: doublets and triplets — thin opal
slices on a backing, with or without a clear cap — are widely sold in fashion
jewellery. Verification that opal is solid rather than composite is essential before
assessing value. [2]
Coober Pedy White Opal
The world's largest opal field:
Source
Characteristics
- Body colour: White to light grey (N7-N9)
- Play-of-colour: All colours possible
- Volume: Vast majority of Australian production
- Quality range: Commercial to fine
White Opal Quality
Quality factors in white opal:
Body Tone
- N7-N9 on body tone scale
- Lighter background than black opal
- Less contrast for play-of-colour
- Some prefer softer aesthetic
Play-of-Colour
- Brightness: Key value determinant
- Coverage: Full face coverage ideal
- Colours: Full spectrum more valuable
- Red presence: Adds significant premium
- Pattern: Similar patterns to black opal
Crystal Opal
Transparent to translucent opal variety:
Characteristics
- Body: Transparent to translucent
- Play-of-colour: Visible through body
- Sources: Lightning Ridge, Coober Pedy, others
- Effect: Depth and dimension to colour display
Black Crystal
- Dark transparent body
- Exceptional light transmission
- Shows play-of-colour with depth
- Premium variety; rare
Light Crystal
- Clear to light grey body
- More common than black crystal
- Beautiful depth effects
- Good value option
Other Australian Opal Sources
Additional white and light opal production:
Andamooka
- South Australian field
- Matrix opal notable
- Some treated (sugar-acid)
- Variable quality
Mintabie
- Northern South Australia
- Quality approaching black opal
- Limited production
- Collector interest
White Cliffs
- Historic NSW deposit
- First major Australian opal field
- Limited current production
- Historic significance
Quality Grading
| Grade | Brightness | Body Tone | Value Range |
|---|---|---|---|
| Gem | Brilliant | N7-N8 | High |
| Fine | Bright | N7-N9 | Medium-High |
| Good | Moderate | N8-N9 | Medium |
| Commercial | Subdued | N9 | Accessible |
Market Position
White and crystal opal in the market:
- Accessibility: Wide price range available
- Volume: Most common Australian opal type
- Fine quality: Can command good prices
- Crystal premium: Good crystal opal valued
- Fashion jewellery: Major market segment
- Treatment note: Some material treated (doublets, triplets)
Doublets and Triplets
References
- ↑ 1. Schumann, W. (2009). Gemstones of the World (4th ed.). Sterling Publishing. ISBN: 978-1-4027-6829-3.
- ↑ 2. Read, P. (2014). Gemmology (3rd ed.). Butterworth-Heinemann. DOI: 10.4324/9780080507224.