There were a few shops just there, I cant think of any that just sold Jewelery? Blacks, Edwards, Griffins, Avrills, Goulds Tailors, The Maypole, The Co-Op are all shops just thereabouts that spring to mind, and were almost opposite to the Jack Built. I know these arnt perhaps what you asked for, but maybe remebering some of the shops round about might help?
There was a Pawnbroker come jewelery/ watch and clock shop on the other side by the name of Biddles?