To cut down on thumb-pierced chocolates, confectioners started inserting indexes, which inevitably get misplaced. Even so, you can make educated guesses: Caramel centers are mostly square, and cream centers are round, says Greg Johnson, manager of technical services for Russell Stover Candies. The exterior chocolate (dark or milk) can also hold clues. High-fat centers—peanut-butter cream, a soft chocolate truffle, buttery toffee— are more likely to be inside milk chocolate, Johnson says. Liquid- and liqueur-filled candies usually have foil wrappers, says Susan Fussell of the National Confectioners Association, in Vienna, Virginia. Heft and scent won’t aid you as you speculate about the filling: Nearly every piece of Russell Stover candy weighs 14 or 15 grams, and the chocolate seals in any aromas. (The only scents that seep out are those of mints, which are usually packaged separately.) The last resort is a return to the start. Thumb piercing. “But after you poke it,” Fussell says, “it had better be going in your mouth!”