9 Most Valuable Collectibles
Global real estate consultancy Knight Frank, which publishes data on the market of high net worth people, compiles indexes of nine collectible markets to track how much each category is rising or falling in price.
Indexes of collectibles are often criticized for being incomplete. Because they are based on sales of illiquid assets, they don't include the pieces that people decide to keep -- which are usually those that don't rise in value.
But the indexes show which categories are trending, and how much you can make if you pick a winner. Click through to see what's trending up.
Selected facts and photos from Knight Frank; other photos from iStock.
-- Elizabeth MacBride