It is a copy of a Venetian gold ducat/zecchino of Doge Francesco Loredan (1752-62).
As far as I am aware, the "Christ in lozenge" reverse was only used on gold coins at this time.
Example on Sixbid/Baldwins.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis