Captain John Gerrish, who was born at Dover, New Hampshire, on 21 August 1668, and died on 21 February 1737, resided in Boston.He married (1) Lydia Watts, and (2) Sarah Hobbes.He was the son of John Gerrish, a judge of Dover, New Hampshire, and Elizabeth Waldron.John, b. 1668, was the grandson of Captain William Gerrish and his first wife, Joanna Lowell.
*Old Boston Families No. 2* by Arthur Wentworh Hamilton Eaton was published in 1913.It tells about John, b. 1668, and his family.Unfortunately, I have only a couple of pages from the book.
The Gerrishes were a prominent New England family.Some of the Bostonian members might have had a coat of arms.Some might have moved to Canada before the Revolutionary War or after.
Best wishes in your search for the origins of the silver cup!