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) that 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.