Eliminating confusion when differentiating between items by color

When choosing colors to display for a list of items (example: Map, Bar or line chart) I have run into the issue of too many colors (13) being used to differentiate between unique items. So my question is how do you prevent confusion amongst the users when the only way to differentiate between items is by color?

Example:

User1: The light pink...

User2: Do you mean the deep peach one?