Sapphire

Associated with diamonds (Ex. 28:18) and emeralds (Ezek. 28:13);
one of the stones in the high priest's breastplate. It is a
precious stone of a sky-blue colour, probably the lapis lazuli,
brought from Babylon. The throne of God is described as of the
colour of a sapphire (Ex. 24:10; compare Ezek. 1:26).