Celebrate April's birthstone with a sparkling journey through the top 10 biggest diamonds ever found: 10 - The Millennium Star 9 - The Red Cross 8 - The De Beers 7 - The Jubilee 6 - The Centenary 5 - The Spirit of Grisogono 4 - The Cullinan II 3 - The Incomparable 2 - The Cullinan I 1 - The Golden Jubilee