the Berasit Hebrew Dictionary

תרשיש

'teresis' is traditionally interpreted as beryl - a translucent crystaline gem ranging from clear to a variety of color. The green variant is generally known as emerald.

In Daniel 10, the prophet Daniel is surprised by the sudden appearance of a strange figure, who he describes as having a “body like 'teresis', his face like lightning, his eyes like flaming torches, his arms and legs like the gleam of burnished bronze, and his voice like the sound of a multitude.”