Easton's Bible Dictionary

Jasper - (Heb. yashpheh, "glittering"), a gem of various colours, one of the twelve inserted in the high priest's breast-plate (Ex. 28:20). It is named in the building of the New Jerusalem (Rev. 21:18, 19). It was "most precious," "clear as crystal" (21:11). It was emblematic of the glory of God (4:3).