Have you been to Lowes or HD and gone thru their books? I'm sure I saw a black shade there when I ordered my woven wood.

When I Googled 'black bamboo shade' I found them online at JC Penney, Overstock.com, and several sites in the UK.

I'd probably find one that I like and spray paint it in a black satin paint, but I love home dec projects!

One think to consider about black grass shades is that they are practically transparent to the dark outside in a lit room. They really give an illusion of privacy they don't provide. I don't want to discourage you from using it, just wanted to make you aware.

Here is a link that might be useful: The Shade Store

totally off topic from black shade sources, but i have got to second what pal says---i've had woven woods in our kitchen for years---definitely don't provide complete privacy, but do give a little bit and very effectively filter the sun...
i placed gorgeous dark brown woven woods in our bedroom this fall-totally different style than our kitchen- and even though i knew they were different style and would be sheerer, i was shocked at how transparent they were-even relatively distant house lights shone through!(and are very transparent from outside looking in). we had our drapes lined with blackout liner and close them most nights!!