In the 1990s, it was estimated that as much as 25 percent of the world’s diamonds were in some way illicit (used for money laundering, tax evasion, purchasing drugs, weapons and other goods, or were stolen).
Source: “Killing Kimberley? Conflict Diamonds and Paper Tigers”, The Diamonds and Human Security Project, Revised Edition, November 2006,pg.3,(accessed: November 13, 2006).