Australian Sapphire
Australian sapphire characteristics including parti-sapphires, dark blues, and comparison with Asian sources.
Introduction
Australia has been a significant sapphire producer since the 1850s, with the first
alluvial recoveries recorded near Inverell, New South Wales. [1]
Major deposits extend across the New England tablelands of NSW (Inverell, Glen Innes)
and the central Queensland gemfields (Anakie, Rubyvale), all hosted in Cenozoic
basalt-related alluvial placers.
The diagnostic signature of Australian sapphire is a high iron content, commonly
exceeding 600–1,000 ppm, which produces the dark, sometimes inky blue tone and
suppresses UV fluorescence relative to marble-hosted Ceylon or Burmese material.
[2] The same basaltic environment generates strong colour
zoning, giving rise to parti-sapphires — stones displaying distinct blue, green,
and yellow sectors — which are virtually unique to this origin and command growing
collector interest.
Heat treatment is widely applied to lighten over-dark material, and is fully
accepted when disclosed. Australian yellow sapphires and chrysoprase from
Marlborough, Queensland — the finest worldwide — broaden the country's commercial
palette beyond the blue corundum for which it is best known. [1]
Sources
Major Australian sapphire regions:
New South Wales
- Inverell: Major production centre
- Glen Innes: Significant deposits
- Character: Alluvial deposits in basalt areas
- History: Mining since 1850s
Queensland
- Anakie: Historic sapphire fields
- Rubyvale: Active production area
- Gemfields: Extends across central Queensland
- Volume: Substantial commercial production
Colour Characteristics
Distinctive Australian sapphire colours:
Blue Sapphire
- Typical colour: Often dark; "inky" appearance
- Tone: Medium-dark to very dark
- Saturation: Can be quite saturated
- Iron content: Higher than Ceylon/Burma [2]
- Treatment: Heat treatment common
Parti-Sapphire
- Character: Zoned colours in single stone
- Combinations: Blue/green/yellow typical
- Appeal: Unique, distinctive appearance
- Market: Growing collector interest
Other Colours
- Yellow: Significant production
- Green: Common; iron-related colour
- Fancy colours: Various shades available
Parti-Sapphire Specialty
Australian vs Asian Sapphire
Australian
- Often darker, inky blue
- Higher iron content
- Less fluorescence
- More green/yellow modifiers
- Lower prices typically
- Parti-sapphires unique
Ceylon/Burma
- Lighter, brighter blue
- Lower iron content
- Better fluorescence
- Purer blue colour
- Higher market value
- Classic sapphire appearance
Treatment
Enhancement of Australian sapphire:
- Heat treatment: Very common
- Purpose: Lightens dark stones, improves colour
- Disclosure: Required; generally accepted
- Unheated: Premium if naturally good colour
- Beryllium diffusion: Some material treated
Market Position
Australian sapphire in the marketplace:
- Volume: Major commercial supplier globally
- Value: Below Ceylon/Burma for comparable quality
- Advantage: Excellent value for money
- Treatment: Common; factor in pricing
- Parti-sapphires: Niche but growing market
- Yellow sapphires: Competitive quality available
Chrysoprase
Australia's other notable coloured stone:
Queensland Source
- Location: Marlborough, Queensland
- Quality: Finest chrysoprase in world
- Colour: Apple green to deep green
- Chromophore: Nickel [1]
Characteristics
- Species: Chalcedony (cryptocrystalline quartz)
- Translucency: Semi-translucent ideal
- Colour stability: May fade in strong light
- Hardness: 6.5-7 (durable for jewellery)
Market
- Premium over other chrysoprase sources
- Fine material increasingly scarce
- Often cut as cabochons
- Some faceted for effect
References
- ↑ 1. Schumann, W. (2009). Gemstones of the World (4th ed.). Sterling Publishing. ISBN: 978-1-4027-6829-3.
- ↑ 2. Palke, A.; Renfro, N.; Berg, R. (2019). Geographic Origin Determination of Blue Sapphire. Gems & Gemology, 55(4), 536–579. DOI: 10.5741/gems.55.4.536.