The highly prized trolls are those with colored eyes. The most common dolls had brown or amber glass eyes. Green and blue glass eyes were later introduced, but were soon replaced by several colors of plastic "spiral" or striped eyes. A troll with colored glass or spiral peepers can command twice the price of a plain brown-eyed doll.
The troll on the left (with purple hair) has hard-to-come-by green glass eyes. The troll on the right has the very popular "spiral" plastic eyes.