"Oh - and fifty for Miss Lovegood, I suppose."
-- Professor McGonagall, giving points for the Battle at the Department of Mysteries (OP38)
The Ravenclaw hourglass in the Hogwarts Entrance Hall for recording House Points is filled with blue sapphires (Pm, OP38).
- Firenze the centaur had "astonishingly blue eyes, like pale sapphires" (PS15).
- The creature known as a Billywig is a "vivid sapphire blue" (FB)
from Greek sappheiros "blue stone"