Historical clue formulations

• Device featured in Newton's "Opticks" — 2025-08-02
• Rainbow creator — 2023-10-29
• Glass that refracts light — 2021-08-02
• Light beam splitter — 2021-02-01
• Glass that makes a rainbow — 2018-10-22
• Certain decorative paperweight — 2018-06-30
• Cover image on Pink Floyd's "The Dark Side of the Moon" — 2017-11-27
• Light beam splitter — 2017-03-15
• Light beam splitter — 2016-07-06
• Object depicted on the cover of Pink Floyd's "The Dark Side of the Moon" — 2016-05-12
• Light shower? — 2015-12-12
• Light splitter — 2015-06-11
• Beam splitter — 2015-01-11
• Light bender — 2014-08-26
• Optical separator — 2014-08-08
• Rainbow maker — 2014-03-25
• Light reflector — 2011-05-29
• Spectrum-forming solid — 2010-03-24
• Light refractor — 2009-02-16
• Light refractor — 2006-09-25
• Periscope part — 2005-02-19
• Spectrum creator — 2002-06-11
• Rainbow maker — 2001-08-24
• Rainbow maker — 2000-08-22
• Light-refracting crystal — 2000-03-27
• Spectrum maker — 2000-01-26
• Geometrical solid — 1997-12-28
• Color separator — 1997-12-09
• Chandelier pendant — 1996-11-03
• Geometrical solid — 1994-08-21