there were a few Jews on the Island pre revestment (eg Philip Levi acted as interpreter), a couple caused 'problems' for the church when they 'converted' in order to marry
Not sure if any stayed after 1765 but in 1830's there was Joseph Saqui brother of a famous cantor and choirmaster in Liverpool who was involved in early Oddfellows, returned to Island as a tobacconist - I believe others came over associated with jewelry trade

I could only find the one ref on my web site but somewhere I'm sure I've seen other references to the Demeza name, catch is that non-Manx names were often mangled so simple searches dont always work