What is the X in X-mas?
(Rev. 4:3, R.V., "sardius;" Heb. 'odhem; LXX., Gr. sardion, from a root meaning "red"), a gem of a blood-red colour. It was called "sardius" because obtained from Sardis in Lydia. It is enumerated among the precious stones in the high priest's breastplate (Ex. 28:17; 39:10). It is our red carnelian.