The colour of a piece of genuine sea glass depends on its origin. While quite a bit of sea glass comes from bottles, some comes from broken ceramics, old jars, even tableware.
The most common sea glass colours are kelly green, brown, and clear. Most of these come from old beer bottles.
Uncommon sea glass colours include jade green, lime green, and cornflower blue, mostly from old soda and alcohol bottles.
Rare sea glass colours include red, black, yellow, and orange. Most of these were originally bottles of a type that weren't broken often!