Related Clues:

• Gem with a changing luster
• Spectrum producer
• Optical body used to disperse light
• Beam splitter
• Optical device
• Piece of cut crystal, perhaps
• Certain marble
• Colorful playing marble
• Lustrous gem
• Spectrum maker
• Periscope part
• Marble type
• Semi-precious stone
• Spectroscope part
• Light beam splitter