From 1986 to 1992, proof Silver Eagle coins were minted at San Francisco and these coins bear the “S” mintmark. From 1993 to 2000, they were minted at Philadelphia and these coins bear the “P” mintmark. From 2001 to 2008, they were minted at West Point and these coins bear the “W” mintmark. No proof versions were minted in 2009. Beginning again in 2010, the proof coins were minted at West Point and bear the “W” mintmark.
From 2006 to 2008 and beginning again in 2011, the United States Mint issued a collectible uncirculated Silver Eagle coin produced at West Point(bearing the “W” mintmark). The coins are struck on specially burnished blanks.
(Source: Wikipedia contributors, “American Silver Eagle,” Wikipedia, The Free Encyclopedia(accessed December 8, 2016).) (Generic product image; not the item you will receive.)