Possible Clues:

• Device used to invert an image
• Glass that refracts light
• Rigidly precise, restricting small source of coloured light
• Political leader holds back gentleman, a solid figure
• Many a paperweight
• Refracting object
• Shape of a Toblerone box
• Glass block that separates light into the colours of the spectrum
• Object that makes a rainbow
• Proper to shield singular source of spectral effects