From LEGO Batman Wiki
LEGO Studs come in four different colors. Blue, gold, purple and silver. Blue ones are 1,000 Studs, Gold ones are 100 Studs, Purple ones are 10,000 studs, Silver ones are 10 studs. You can get them by destroying things on LEGO Batman, LEGO Indiana Jones, and LEGO Star Wars.You can use them to buy things at the batcomputer.