"I'm the 467th-richest person in the world"

Unknown Picasso
Creative Commons Attribution Share AlikeUnknown Picasso - Credit: StrangeInterlude / James Spurrier
Forbes magazine publishes the most famous (or infamous) list of rich people in the world. Their list only goes up to 400 so you can't check Ada Black's claim, but to own two Picassos she'd have to be very, very rich.