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

Noah Webster's New International Dictionary of the English Language

(n.) An opaque, impure variety of quartz, of red, yellow, and other dull colors, breaking with a smooth surface. It admits of a high polish, and is used for vases, seals, snuff boxes, etc. When the colors are in stripes or bands, it is called striped / banded jasper. The Egyptian pebble is a brownish yellow jasper.