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Iolite

Known since the time of the Vikings, Iolite was considered a collector’s stone before the 1980’s as it was very little used in the jewellery trade.  It has been known by a number of names including cordierite, dichroite and also water sapphire.
Today it is much more popular due to its attractive deep blue to violet colour.  For this reason; it is sometimes referred to as ‘water sapphire’ and is used as a more affordable, untreated and natural substitute for both sapphire and tanzanite.  It is commercially mined in India, Sri Lanka, Tanzania and Brazil. 

   
Mohs’ Hardness: 7-7.5
Specific Gravity: 2.53-2.66
Refractive Index: 1.537-1.551
Birefringence: 0.008-0.012
Optic Sign & Character: Biaxial Positive/Negative
Treatments: None
Durability: Good
Special Care: Normal care
Synthetics: None
Possible Imitations: Synthetic Corundum and Glass