Historical clue formulations

• Certain shooter — 2015-02-27
• Certain shooter — 2009-05-02
• Certain marble — 2008-05-14
• *Colorful marble — 2006-11-01
• Colorful marble — 2006-09-05
• Pretty marble — 2005-07-27
• Gem with a changing luster — 2002-12-20
• Colorful marble — 2002-09-24
• Shooter's target — 2001-12-14
• Marble with concentric circles — 2001-09-08
• Colorful playing marble — 2000-04-06
• Pretty marble — 1998-09-29
• Relative of an agate — 1997-07-20
• Marble — 1994-12-25