Historical clue formulations

• Iridescent shell material — 2026-04-05
• Iridescent jewelry material — 2026-01-11
• Component of a nautilus shell — 2025-12-26
• Inlay material on some guitars — 2025-08-22
• Mother-of-pearl — 2025-05-08
• Iridescent material — 2025-02-28
• Shiny button material — 2023-12-23
• Pearl button coating — 2023-05-21
• Shiny material in some guitars — 2023-01-13
• Source of iridescence in many mollusks — 2022-12-01
• Mother-of-pearl — 2022-04-13
• Lustrous shell compound — 2021-09-24
• Shiny button material — 2021-05-19
• Shell material — 2019-11-02
• Mother-of-pearl — 2019-05-26
• Mother-of-pearl — 2019-03-24
• Guitar inlay material — 2019-03-10
• Mother-of-pearl — 2018-12-13
• Button material — 2018-10-19
• Iridescent material — 2018-01-12
• Mother-of-pearl — 2017-10-01
• Mother-of-pearl — 2017-07-09
• Button material — 2015-07-26
• Nautilus shell feature — 2014-11-21
• Mother-of-pearl — 2014-05-13
• Abalone shell lining — 2014-03-26
• Iridescent material — 2013-03-30
• Decorative inlay material — 2013-01-30
• Mosaic material — 2012-11-11
• Brooch feature, maybe — 2012-06-17
• Mother-of-pearl — 2012-03-26
• Inlay material — 2011-06-08
• Mother-of-pearl — 2011-05-31
• Inlay option — 2011-01-29
• Necklace decoration — 2008-11-22
• Inlay material — 2008-08-20
• Decorative inlay material — 2008-01-06
• Mother-of-pearl — 2007-09-19
• Mother-of-pearl — 2006-06-05
• Certain shell liner — 2005-09-30
• Inlay on some guitars — 2005-04-01
• Button material — 2004-03-21
• Button material — 2003-12-22
• Mother-of-pearl — 2003-07-14
• Mother-of-pearl — 2001-07-30
• Abalone production — 2000-09-30
• Bead material — 1999-05-27
• Button material — 1998-03-08
• Mother-of-pearl — 1997-12-01
• Button material — 1997-05-25