This Christmas tree topper made of Waterford crystal was given to my wife and me about thirty years ago. Sadly, we've never been able to use it because it is too heavy to use on a real or artificial tree.
Unlike most materials that merely reflect color, cut glass will produce color when it acts as a prism as in this case.
EDIT: A second image of the same subject has been added later in the thread.
Setup
The background is black felt, though I could have used anything including a white board and the background still would have appeared black. A circular diffuser considerably larger than the background is immediately behind the background. The tabletop is glossy black acrylic. A large continuous-light lamp with five bulbs lit was shining from behind the diffuser and background toward them, the subject and camera. A black card with a rectangular hole cut in the middle was placed in front of the lens to minimize flare and maximize contrast. The subject is rotated at the angle that disperses the most color in the prismatic refraction.