Having the color of a blue sapphire.

ETYM Old Eng. saphir, French saphir, Latin sapphirus, Greek saphiros, of Oriental origin; cf. Hebrew sappîr.
1. A precious transparent stone of rich blue corundum valued as a gemstone.
2. A transparent piece of sapphire that has been cut and polished and is valued as a precious gem.
Deep-blue, transparent gem variety of the mineral corundum Al2O3, aluminum oxide. Small amounts of iron and titanium give it its color. A corundum gem of any color except red (which is a ruby) can be called a sapphire; for example, yellow sapphire.