The Brown-Driver-Briggs dictionary defines hashmal as "a shining substance, amber or electrum or bronze." The Revell Bible Dictionary says, "While the root meaning remains uncertain, all scholars agree that the image, used to describe the visible glory of God, conveys the sense of brilliance." Ancient Greeks called amber "electrum." The Elder Pliny (23-79 AD) described amber's magnetic attraction, how that when rubbed it would become electrically charged and attract such things as straw, hair, dry leaves and feathers. Amber is one of the oldest gemstones, having been found in archaeological digs of tombs dating to the Stone Age.
The most valued amber (even today) is that which contains an inclusion of an insect.
Large amounts of agate have been found in archaeological digs of Sumer, dating back to 3500 BC.
Theophrastus (372-287 BC) appears to have been the first man to write about agates.
Historians have likened it to “a thousand leagues of sunlit sea imprisoned in a cup.” It’s very name is descriptive of it’s color: aqua meaning water and marine meaning sea.