Experts say the $100 million jewels stolen from the Louvre may already be lost forever. Investigators fear the thieves will melt down or break apart the historic royal gems � including crowns, necklaces, and brooches � to sell the pieces discreetly on the open market. �It could be sold down the street from the Louvre,� said art crime expert Erin Thompson, noting that cutting or recasting the gems would erase their traceability and historic value.