If you read the ingredients on the Coca-Cola bottle, you will see: 1. Carbonated water , II. Corn syrup with more fructose sugar , 3. Caramel color , 4. Natural flavor , 5. Caffeine etc. It is worth mentioning here that Coca-Cola mixes some more secret formulas with these common ingredients , which they will never reveal. However, the general idea is that the dark brown color came as a result of mixing brown caramel. If you read the contents of the sprite bottle, you will see that there is no caramel mixed in it. That is why the color of the sprite is transparent.