Summary: Easily concealed and transported, and virtually untraceable to their original source, diamonds are often used in lieu of currency in arms deals, money laundering, and other criminal activity. U.S. controls over diamond imports only require certification from the country of last import--and thus cannot identify diamonds from conflict sources. Although the United States bans diamonds documented as coming from the National Union for the Total Independence of Angola, the Revolutionary United Front in Sierra Leone, and Liberia--all of which are subject to U.N. sanctions--this does not prevent such diamonds from being shipped to a second country and mixed into parcels destined for the United States. GAO found that the Kimberley Process's proposal for international diamond certification incorporated some elements of accountability. However, it is not based on a risk assessment, and some high-risk activities are subject only to "recommended" controls. Also, from the time when rough diamonds enter the first foreign port until the final point of sale, there exists only a voluntary industry participation and self-regulated monitoring and enforcement system. These and other shortcomings significantly undermine efforts to deter trade in questionable diamonds.