I can't really give you tips on names...my character names for another fanverse are: Ramu, Chanse and Stripey the Zebra...-not exactly creative.
However I can respond that NO ONE, despite what some people may think, can copyright colours. However with the design of ''Sigg'', I do think that maybe you might be better with changing the design that you wanted for your own character so it is seperated from Sigg....and that you will not get nasty flames from the artist and his/her followers who say along the lines: 'OMG, you stolez my character, you must die''... I have seen these types of things before, never been on the receiving end, and they are just pathetic. However, I do recommend that whilst keeping the colours, you change the entire design that suits you and the character.
I hope this is okay for you. I know how hard it is to have a character for colours; I have a purple and blue lioness..and when I see other people's characters with the same colours, i don't mind especially as the design isn't like my character's.