Answer: is very rare. In fact, people of other religion than catholic (or christian in other countries like Russia or England, etc) were not allowed to get titles mostly until the end of the XIXth. But at those times most aristocracies were weakened up and new titles rarely given away. Exception is the Rothshild banker family, who gets the French title of baron after helping Napoleon to finance the campaign to Russia. But, there are a whole lot of aristicratic families marrying jews, mostly (to be very honest) for financial reasons. Thus, twice the banker family Lazard getting married into the de la Fressange family. Some converted jews manage to get titles in Spain, mostly in the management of colonies, like the first governor of Indias Pedro Arias de Avila. On top, it is most probable that many pretendants to titles in Spain hide away their jewish origins by preteding to be visigothic. For example the noble Checa family from Aragon gets the title after a member of aristocracy having sworn they are of old visigothic family (???). Of jewish origin is also to lower aristocracy (fijosdalgo) belonging family of Santa Teresa de Jesús.