They sparkled like the blue dress and diamonds.
The largest and most productive field is that of Diamantina on the head-waters of the Jequitinhonha River, where diamonds were discovered about 1725, and where the celebrated "diamond reservation" - an oval-shaped territory 8 leagues wide by 16 leagues long (Mawe), with Tejuco, now Diamantina, very nearly in the centre - was established in 1730.
The exports cover a wide range of agricultural, pastoral and natural productions, including coffee, rubber, sugar, cotton, cocoa, Brazil nuts, mate (Paraguay tea), hides, skins, fruits, gold, diamonds, manganese ore, cabinet woods and medicinal leaves, roots and resins.
Diamonds were discovered in Minas Geraes, near the town now called Diamantina, during the first half of the 18th century, the dates given ranging from 1725 to 1746, but the productiveness of the district has greatly decreased.
The Sand River Convention of 1852 had not defined the western border of the state, and the discovery of gold at Tati to the northwest, together with the discovery of diamonds on the Vaal in 1867, offered Pretorius every inducement to extend his boundary.