Another silversmith stamp from my collection is even older than the Staniford example posted earlier. Though the counterstamp is unevenly struck and heavily worn, it's easily assigned to Massachusetts silversmith William Swan. I've attached an example of the complete stamp pictured online, plus an alternate mark of Swan's.
Swan was born in Charlestown on April 18, 1715. His father, Ebenezer, died when William was only a year old, so he was raised by his mother Prudence.
I found no record of who he apprenticed with but was in the trade in Boston by at least 1740. His tenure there lasted until 1752 when he removed to Marlborough. Spending only two years there, he moved on to Worcester in 1754. It's uncertain how long he practiced in Worcester as I found no record of him past 1755, at least not as a practicing silversmith. However, he remained a resident of that city until his death on May 4 ,1774. A notice of his passing appeared in the May 5th edition of the "Boston Weekly News-Letter" where he was described as "Goldsmith, formerly of Boston, a man of a very respectable character." He was survived by his wife of thirty years, Levinah Keyes Swan.
Two other pieces of information came to my attention in regard to his years in Worcester. He was appointed Clerk of the Market in 1772 and Sealer of Weights and Measures a year later in 1773.
Three examples of Swan's work were found online. A covered cup dated 1749 now in the Essex Institute, a porringer c 1750 in the collection of the Winterthur Library, and a silver cream pot c 1755 housed at the Museum of Fine Arts in Boston. The pot was engraved KC (Katherine Chandler Willard) and JM (her son John Willard). The covered cup was engraved "THE / Gift of Province of the / MASSACHUSETTS / BAY / TO / Benjamin Pickman, Esq' / 1749" with the Pickman family crest on the back. The porringer was engraved "V" over "EL" over "OL to PL." These are initials of unknown persons, but was likely a wedding gift or something of that nature
The counterstamp in struck on a heavily worn George 2nd halfpenny of unknown date. These coins were minted from 1727 until 1760. Taking into account the extreme wear on the coin and the stamp, I would guess that it was applied sometime during his 1749 / 1753 tenure in Boston. A very old American silversmith mark indeed.
Bruce