The end segment should be a purple colour to match the rainbow pattern. Violet comes next. Every wondered why we split the rainbow in to 7 colours? You can split it in to any number (we used 6). It was Isaac Newton who chose 7: because the Ancient Greeks thought 7 was a ‘magic’ number found in nature. Newton was interested in magic and thought the Greekswere right so he gave the rainbow 7 colours, splitting purple in two.
A bit of cs4fn 