DiorShow Mascara comes in a beautiful color called Chestnut which is a soft brown that would definitely not be as harsh as using a black mascara. You can find it at: http://sephora.com/browse/product.jhtml?id=P40404&
Another thing you may want to try instead of changing mascaras is to wear a soft brown eyeliner with your black mascara so that the dark eyeliner and mascara don't work together to look so harsh.
I hope this helps you.
You can try brown mascara if you don't like how the black mascara looks -- or even a clear mascara if you prefer a very natural look.
Clinique Naturally Glossy Mascara in Jet Brown is a good one to try (http://www.sephora.com/browse/product.jhtml?id=P12
There is also Sephora brand clear mascara: http://www.sephora.com/browse/product.jhtml?id=P40
I use black mascara on 80 percent of my clients. One client that comes to mind when I think of whom not to use it on is Molly. She always had these super thick, long butter blonde lashes, so black looks funny on her. We agreed to use Lancome Definicil's Mascara in Brown, and she liked the way that looked.
I'm a strawberry blonde w/ blonde eyelashes. I'm very fair skinned. I've never chosen to wear black eyeliner (when I modeled, they just put their make-up on and I sat there.); I occasionally wear black mascara but usually I wear brown. I like it much better. Somedays I just curl them. As far as using a clear mascara, I would try a drugstore brand and see if you like it before investing money into one. For me it didn't really do anything. Good luck, hope this helps.