Definition of "night-blue" [night-blue]

• A trade-name for a blue which retains its color under artificial light. (noun)

The Century Dictionary (Public Domain)

• "The clear water got deeper, then shallow again, as they raced over iridescent carpets of night-blue mussels."
• "Resplendent in her glittering night-blue dragon-scale armor, Kitiara stepped haughtily to one side as Tanis walked through the ornate doorway into the Hall of Audience."
• "His hand shaking, he reached for the next night-blue bound book in the huge pile he had amassed at his side."