When the term ‘sapphire’ is used by itself, it is assumed that it is referring to the blue variety of sapphire. All other colours of sapphire are denoted by their colour first, for example ‘green sapphire’. More specifically in the Australian gemstone and jewellery trade, the name ‘sapphire’ refers to Australian type blue sapphire as it is the most commonly used.
Sapphire mining in Australia began in the late 1800’s at Anakie in Central Queensland. Since then, mining centred at Anakie has spread to the surrounding sapphire bearing fields of Rubyvale, Sapphire and the Willows with the whole area collectively known as the central Queensland gemfields. The central Queensland gemfields are considered to be one of the richest deposits of sapphire in terms of volume in the world.
While Queensland is renowned for its high production, the sapphire bearing region of northern New South Wales known as New England is known for the highest quality. Some of the important sapphire mining areas of the New England sapphire fields include; Glen Innes, Inverell, Reddestone and Kings Plains. While Australian sapphire is well known for its darker royal blue tones, other types available are yellows, greens, parti coloureds and star stones.
Mohs’ Hardness: 9
Specific Gravity: 3.99-4.01
Refractive Index: 1.760-1.774
Optic Sign & Character: Uniaxial Negative
ICA Code: N or E
Purpose: To lighten or darken colour and improve clarity
Durability: Very good
Special Care: None
Synthetics: Flame fusion, hydrothermal or flux melt
Possible Imitations: Glass, CZ, synthetic spinel, doublets