A sapphire is a precious stone which is blue in colour.
...a sapphire engagement ring.
2. colour
Something that is sapphire is bright blue in colour.
[literary]
...white snow and sapphire skies.
sapphire in British English
(ˈsæfaɪə)
noun
1.
a.
any precious corundum gemstone that is not red, esp the highly valued transparent blue variety. A synthetic form is used in electronics and precision apparatus. Formula: Al2O3
b.
(as modifier)
a sapphire ring
2.
a.
the blue colour of sapphire
b.
(as adjective)
sapphire eyes
Word origin
C13 safir, from Old French, from Latin sapphīrus, from Greek sappheiros, perhaps from Hebrew sappīr, ultimately perhaps from Sanskrit śanipriya, literally: beloved of the planet Saturn, from śani Saturn + priya beloved
sapphire in American English
(ˈsæfaɪr)
noun
1.
a clear, deep-blue variety of corundum, valued as a precious stone
2.
its color
3.
a.
a translucent or transparent variety of corundum, varying in color
b.
a gem made of this
white, yellow, and purple sapphires
adjective
4.
deep-blue
Word origin
ME < OFr saphir < L sapphirus < Gr sappheiros < Heb sapir < Sans śanipriya, lit., dear to Saturn < Śaniḥ, Saturn (the planet) + priya, beloved < IE *prī-, var. of base *prēi-, to love > friend