Well, as you can see Rihanna is an actress and singer from Babados, a Carribean island country. As a matter of fact, she originally has got a pair of black eyes, however, in order to appear more attractive in public and shows, she chooses to wear contact lenses, especially grey colored contacts which would not be artificial like blue contacts. You can find those contacts at every optical stores, or Amazon and Alibaba.
From the pictures, rihanna wears the hazel and green contact lenses. If you are interested on these two colors, you could go to the online stores to have a search. I strongly suggest you to go to the online stores with good reputation, like amazon and walmart which will provide you the one with good quality.
I have to tell you she possessed several kind of contact lenses with different color.I have saw her eyes in different color.If you want to buy a similar one like one of hers,buy it oneline would be a very wise choice.
Here is my suggestion.Firstly,you need to login on ebay or amazon ,or the other online shopping web.Secondly,insert such words"contact lenses like rihanna "in the search bar.Thirdly, you can see a plenty of merchandise show up with her picture,then you can have a quick look,then shortlist them.Finally,you can choose the one you like most.