What is the X in X-mas?
properly a flower of a reddish blue or deep purple (hyacinth), and hence a precious stone of that colour (Rev. 21:20). It has been supposed to designate the same stone as the ligure (Heb. leshem) mentioned in Ex. 28:19 as the first stone of the third row in the high priest's breast-plate. In Rev. 9:17 the word is simply descriptive of colour.
a red, orange, or yellow variety of the gemstone zircon (q.v.).