Question
does the black rose exist? If so where can i purchase them.

Answer
Black Roses (roses of black color) do not exist in nature as such, but nevertheless they are often featured in fiction with many different meanings. The flowers commonly called black roses are actually a very dark red color, such as the "Black Magic", "Barkarole", "Black Beauty" and "Baccara" varieties of roses.

Nature doesn't make truly black flowers, the closest "black" you will get in a flower is actually a black pansy, which is actually what I would consider black.  And what breeders consider black, is usually a very dark purple or a very deep dark red.  

So the only black rose you would be able to order would be a silk one and they sell them at the link below:

http://www.br.org/

So sorry for the truthful disappointment, maybe someday they will actually hybridize a truly black rose, but they have been trying for centuries to no avail.