This is fascinating. Do you have any good reads on this topic?
You've just described a large part of why Jews are so prominent in gem and jewelry trade. If a family's real estate and capital wealth are seized by Christian rulers, jewels and precious metals are the best value-by-weight to sneak a portion of it out during a pogrom.
The other reason is the Christian historically yes-and-no relationship with usury (banking).
Yes, absolutely, and it goes back farther than criminals. Why do you think everyone's grandma has a jewelry collection, while less of the youth do? Because before the 70s, women were not allowed to have their own bank accounts. Their gold and jewelry was the only type of wealth they could keep for themselves.