I have not been able to find an accurate identification for Leo's aviator type sunglasses in the movie Blood Diamond. Note that they have straight arms over the ears, so they are not easily identified.

http://www.celebrity-sunglasses-finder.com/Leonardo-DiCaprio-Sunglasses....

http://fashion.sunglasses-shop.co.uk/forum_posts.asp?TID=386

http://www.iselljerseyshore.com/SHOTS/blooddiamond1.jpg