as kempies link tells you,you have to trade to get a different coloured star,the more you sell or buy the nicer colour you get,quite truthfully the colour is of little meaning really,its your score people take notice of,so the more positive feedback the better.
anyone checking the feedback of a seller should check what type of transactions have been made to get their 100% feedback. i have heard rumors that people buy lots of 1p items to get a good 100% feedback with lots of deals done ( many stars ) then 'sell' one big item and dissappear with the money and buyer ends up with no goods !!!!
anyone else heard of this?