The deep blue of the stone hides some strange properties. Under ultraviolet light, a blue diamond emits a blue glow. However, the Hope Diamond glows red. This unique phosphorescent signature indicates trace nitrogen among the boron and carbon. This special mix formed into a stone over a billion years ago under Earth’s surface. Today, it is set in a necklace. The blue stone is surrounded by 16 white diamonds and its chain contains 45 more stones.