1600's Jesuit / Sulpician Oval Ring - IXXI

The Jesuits were in St.Ignace the Mid 1600's until early to mid 1700's..
When I was selling the IXXI rings on Ebay a few scholars wrote mw with some interesting information on this symbol (The ring is a Sulpican ring rather than a Jesuit ring and the superimposed "AM" stands for "Auspice Maria" which translates to "Under the protection of Mary". )