'Water sapphire' definitions:

Definition of 'water sapphire'

(from WordNet)
noun
A deep blue cordierite often used as a gemstone

Definition of 'Water sapphire'

From: GCIDE
  • Water sapphire \Wa"ter sap"phire\ [Equiv. to F. saphir d'eau.] (Min.) A deep blue variety of iolite, sometimes used as a gem; -- called also saphir d'eau. [1913 Webster]