It's important to note that while the Cullinan is the largest diamond ever found, it wasn't found in alluvial deposits. It was discovered in a kimberlite pipe, the source rock for diamonds.
However, the Cullinan is considered an alluvial diamond because it has been transported and eroded from its original source. The diamond was eventually cut into nine major stones and 96 smaller diamonds, including the world-famous Star of Africa, which sits on the Sovereign's Sceptre.
