A misleading term for both suitably colored synthetic sapphire and spinel, which are used to create alexandrite doublet.
See Alexandrite Tsarstone collectors guide, Definition of Alexandrite doublet, http://www.alexandrite.net/viewpage.html?id=GG-086-00004 (A misleading term for both suitably colored synthetic sapphire and spinel, which are used to create alexandrite doublet.) (as of Feb. 08, 2012, 14:57 GMT).