Velvet coffin or velvet cage?

I've heard "the velvet coffin" used to describe a loveless marriage to a wealthy man. The woman, either a younger, gold-digger type or a wide-eyed innocent, is surounded with luxury and opulance, but her need for love and romance is unfulfilled.
Also, "the velvet coffin" has been used to describe prison for the well connected. I suspect this is mainly a product of fiction, but lots of ganster movies portray the higher-ups of the Cosa Nostra wearing silk pajamas, drinking wine and cooking their own food in a specially equipted cell with a refrigerator, stove, TV, et.al.

= Thanks but are you really talking about the velvet coffin? Seems like you are referring to the velvet cage. Pls confirm,thanks