I was under the impression that the kruggerand has 1 troy ounce of pure gold with additional alloy to give it strength. As a result, a Kruggerand is slightly larger than other gold coins.
http://en.wikipedia.org/wiki/Krugerrand
From Wikipedia:
The Krugerrand is 32.6 mm in diameter and 2.74 mm thick. The Krugerrand's actual weight is 1.0909 troy ounces (33.93 g). It is minted from gold alloy that is 91.67% pure (22 karats), so the coin contains one troy ounce (31.1035 g) of gold. The remaining 8.33% of the coin's weight (2.826 g) is copper (an alloy known historically as crown gold which has long been used for English gold sovereigns), which gives the Krugerrand a more orange appearance than silver-alloyed gold coins. Gold alloy coins are harder and more durable, so they can resist scratches and dents.