I don't think I'd go with prisms. I don't know how you feel about fabric shades, but I think this one from Restoration Hardware would look lovely.

It's kind of hard to get the true feeling of your room from the picture because we can't really pick up the details. I may be out in left field, but I kind of feel like your space is screaming out for some sort of quirky colored light. It's hard to tell if you have an accent color in the space...I spy an orange something in the corner. A google search of "orange chandelier" came up w/ nothing...go figure? I can't really find anything exactly right but maybe something vintage...

http://cgi.ebay.com/Cool-Mod-Vintage-Chandelier-Swag-Lamp_W0QQitemZ230224866862QQihZ013QQcategoryZ46287QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

or maybe something like this...

http://www.carolinarustica.com/product.asp?pn=65693&track=sc&bhcd2=1203541321

There's a 50s Antique French Chandelier listed on AT's classifieds & Craigslist. It looks pretty great.

http://newyork.craigslist.org/mnh/fur/577389661.html

check out the crystal chandelier at brocade home. http://www.brocadehome.com/bh/catalog/product/product_detail.jsp?productId=bh_prod103009&link=leftnav&navAction=jump&navCount=14&categoryId=bh_cat103001

Instead of $600 crystal chandeliers, my boyfriend and I went for the same effect with acrylic crystals and saved hundreds of dollars. We have two chandeliers bought at Goodwill that we painted soft pastels and hung crystals and beads from . You can get very realistic, beautiful crystals from Cristalier
http://www.cristalier.com/
I learned how to design the styles of the lamps by simply looking at images of those $600 versions...good luck!

I say go with something dramatic. I think this would look beautiful against your purple walls...

http://www.gallery840.com/PurchaseLighting.aspx?ID=528