While Brazil is widely known for the production of colored gemstones, it is often not recognized as a source of gem diamonds. Yet diamonds were discovered in the early 1700s by artisanal miners looking for gold along the banks of the Jequitinhonha River near the village of Arraial do Tijuco (later named Diamantina) in the state of Minas Gerais. For the next 150 years, Minas Gerais was the world’s major supplier of gem diamonds. Beginning in the early 1840s, unusual polycrystalline black diamonds (or carbonados) were also recovered, mainly from the state of Bahia.
Brazil in the 15th century
The first European explorers to reach the New World in the late 1400s were focused on finding spices and gold rather than diamonds. The Italian explorer and navigator Christopher Columbus set sail under the Spanish flag in 1492 in search of a more direct route to the “Indies,” the region of the Indian subcontinent and eastern Africa that was rich in spices, gemstones, pearls, and gold.
After a five-week westward voyage, Columbus discovered an island in the Caribbean and called it San Salvador. Portugal and Spain, the global powers of the day, understood that to avoid future confrontation, they had to subdivide the recently discovered lands in the New World. The Treaty of Tordesilhas, drawn up by Pope Alexander VI and signed by the two empires in 1494, drew a meridian that would effectively divide South America (which had yet to be discovered by Europeans) from north to south.
Spain would receive the lands west of the meridian, including modern-day Venezuela, Colombia, Ecuador, and Peru, while Portugal gained the eastern side. On his third trip to the New World in 1498, Columbus discovered the mouth of the Orinoco River in what is today Venezuela. Here was the key to reaching a vast continental interior concealed in the jungles behind the Atlantic coastline.
To open a new trade route to India that did not require passing through the Mediterranean, Portuguese nobleman Pedro Álvares Cabral was dispatched in early 1500 with a fleet of ships. His mission was to reach India by traveling south around the tip of Africa. His fleet landed instead on the coast of Brazil, which he claimed for Portugal on April 22 of that year.
The voyages of Amerigo Vespucci, the Florentine navigator after whom the continent is named, took place around the same time. As he sailed south along the Brazilian coast, Vespucci realized that the continent was much larger than previously recognized. These expeditions were the first to bring back shipments to Portugal of pau brasil (Brazilwood), a tree sought after not only for timber but for a desirable red dye. Over the next two centuries, more European adventurers came to South America, most of them seeking riches in the form of gold, silver, and emeralds.
Portugal’s role in Brazil
Between 1534 and 1536, King John III of Portugal divided the coastal regions of Brazil into 15 captaincy colonies to encourage development; these areas were given to Portuguese noblemen to administer and explore. Within a few years, most of these captaincies failed for a number of reasons. With this setback as well as the presence of French ships along the coast, the Portuguese crown decided to turn Brazil into a royal enterprise in 1549. Several successive governors-general were appointed to administer the colony, which was divided in 1621 into the states of Maranhão (in the north) and Brazil (in the south).
The exploration of Brazil’s vast interior was left to Portuguese adventurers, known as bandeirantes (flag bearers), who claimed territories for Portugal and the Catholic Church. While Spanish conquests in the New World met resistance from powerful empires—the Aztecs in Mexico and the Incas in Peru—the Portuguese were confronted with numerous small native tribes and a forbidding interior.
Exploration and conquest on both sides of the Tordesilhas meridian would soon rewrite the gemological texts of the time. For example, Spanish exploitation of emeralds in the territory of New Granada (modern-day Colombia) would vastly change the world’s understanding and appreciation for the gem, particularly in Europe. Brazil would emerge as a major source for dozens of colorful gem species. It would also become, for a period, the world’s most prolific source of diamonds.
Much of the early exploration and colonization of Brazil was undertaken by the bandeirantes. The bandeiras, funded by the crown and the Catholic Church, were large quasi-military expeditions comprised of hundreds of free men and slaves who ventured into the interior, capturing and enslaving indigenous groups they encountered.
Along with a Jesuit priest, explorer Francisco Bruzo Espinoza mounted the first bandeira in 1554, in search of emerald. It was a short-lived and fruitless expedition. Successive expeditions also failed, though in 1572 Sebastião Fernandes Tourinho found green and blue gems (likely tourmaline) along the tributaries of the Jequitinhonha and Doce Rivers in what is now Minas Gerais. The success of Tourinho’s discoveries attracted more adventurers.
In 1695, at Rio das Velhas, Manuel Borba Gato finally discovered gold, triggering a rush that would lead to the settlement of Vila Rica (later Ouro Preto) in 1698. The town played a leading role in Brazilian history for the next two centuries as the capital of Minas Gerais from 1720 to 1897. Settlements at Mariana, São Bento, Serro Frio, and Arraial do Tijuco soon followed the gold discoveries in those areas of Minas Gerais, and dozens more sprang up in Brazil’s interior.
The north-south road system in Minas Gerais, known as the Estrada Real or “royal highway,” begun in 1697, was built to promote trade, economic development, and communication. Minerals, wood, and other natural resources were transported along the road from the interior to the coast for shipment to Lisbon. Manufactured goods from Portugal were also carried inland. The road was strictly regulated by the crown to prevent smuggling and unauthorized movement of goods. It was also the only official route for traveling inland.
As Brazil’s population grew from European settlement, larger farms were required to grow crops, and indigenous tribes were used as a source of slave labor. Slaves were also imported from Portugal’s African colonies to work the farms. The combination of slave labor and the colony’s immense wealth of minerals and wood provided Portugal with unique imports for the European market .
Early reports on diamonds from Brazil
Early indications of Brazil’s diamond potential were sporadic, but there is evidence that crystals were found in Bahia within a century of Columbus’s discovery of the New World. In one of the earliest descriptions, historian Pero de Magalhães Gândavo (1576) mentioned the existence of “certain mines of white stones such as diamonds.” In another account, Gabriel Soares de Sousa (1587) noted that fine, eight-sided crystals—possibly diamond—had been found during the dry winter months along certain rivers.
English adventurer Anthony Knivet, who was captured and later escaped during a raid of Portuguese settlements in southern Brazil led by the English privateer Thomas Cavendish, described seeing what he believed to be diamond crystals while living among the natives in the late 1590s. This would have been another of the earliest accounts of Brazilian diamonds, though no details were provided and the crystals could have been other gems such as quartz.
In 1695, gold was discovered in the mountainous region near Ouro Preto, and over the following decade thousands of miners flocked from the coast to the interior in search of the precious metal.
Near the village of Arraial do Tijuco in the northern part of Minas Gerais, unusually bright transparent crystals kept showing up in the panned river gravels in the early 1700s. In some cases, the miners disregarded them. Dos Santos recalled that men sometimes used these crystals as small markers in card games. A similar account says that in 1721 a gold miner secured several of these markers, which were later recognized as diamonds by someone who had traveled in the Golconda region of India.
The discovery of Brazilian diamonds is supported by the account of the Dutch explorer Jacob Roggeven (or Roggewein). As reported in Kerr, Roggeven’s three ships anchored off the coast near São Paulo for a short time in November 1721 before resuming their voyage to the Pacific Ocean. Several crewmembers deserted to go to the diamond mining area:
A little time before the arrival of Roggewein, the Portuguese had discovered a diamond mine not far from St Sebastian, of which at that time they were not in full possession, but were meditating an expedition against the Indians, in order to become sole masters of so valuable a prize; and with this view they invited the Dutch to join them, promising them a share in the riches in the event of success. By these means, nine of our soldiers were tempted to desert. I know not the success of this expedition; but it is probable that it succeeded, as great quantities of diamonds have since been imported from Brazil into Europe. They are said to be found on the tops of mountains among a peculiar red earth containing a great deal of gold; and, being washed down by the great rains and torrents into the vallies, are there gathered.
Eventually, reports of diamonds in Minas Gerais began to reach Europe. Accounts from the colonial governor came to the attention of both King John V and the Catholic Church in Portugal, and the discovery was officially announced in 1729. As Lisbon’s economic clout in Europe had waned somewhat, this was welcome news.
In Minas Gerais, there was a diamond rush in the many rivers and streams around Arraial do Tijuco. Portugal moved aggressively to control the area, restricting gold and diamond mining and imposing high taxes. Despite efforts by the crown, clandestine mining and diamond smuggling increased. Draper noted:
The diamonds played a prominent part in shaping the destiny of Portugal. Wealth derived from its diamonds not only helped place that country at the zenith of its glory but also contributed, at a later stage, to its release from the French occupation by paying part of the indemnity exacted by France during the Napoleonic wars (1807-1814).
The occurrence of alluvial diamonds around Arraial do Tijuco was reported in the scientific literature by de Castro Sarmento. Over time, Arraial do Tijuco became the town of Diamantina, the diamond trading center during Brazil’s tenure as the world’s leading exporter. To properly dredge, reroute, and mine the rivers around Diamantina required hard manual labor. This need coincided with the growth of the sugarcane business in Brazil’s northeast, and slaves were imported from modern-day Angola, Congo, and Mozambique to fill the needs of both industries. Much like Ouro Preto, Diamantina grew into a rich and picturesque city in the 18th and 19th centuries.
42,000 carats per year from Brazil to Europe
Oakenfull reported that between 1732 and 1771, “at least 1,666,500 carats of diamonds were exported to Europe.” That figure represents an average of about 42,000 carats per year.
While miniscule by today’s standards, it placed Brazil squarely as the world’s top diamond producer at the time, eclipsing India’s Golconda region. The glut of Brazilian diamonds pouring into Europe caused a steep decline in prices for a time. Consequently, there were efforts to protect the value of the Indian diamonds on the market by disparaging the quality of Brazilian diamonds.
Oversupply was put to an end in 1739 when Portugal stepped in to monopolize the Brazilian mines, but by then the Golconda mines had stopped producing. An arrangement with financiers in Amsterdam ensured a steady supply of Brazilian rough for the city’s diamond cutters. And despite Portuguese oversight, smuggled Brazilian diamonds also found their way to London, another major center for rough diamonds and jewelry production.
During this period, additional alluvial sources were discovered. Diamonds were found in the Mato Grosso region in 1746, and subsequently in other rivers in Minas Gerais. The Jequitinhonha River near Diamantina and the surrounding area yielded impressive quantities of alluvial diamonds as well (figure 8), including treasure troves in “potholes” or traps in the river bedrock. But the primary source of diamonds in Minas Gerais—actual diamondiferous kimberlites—remains elusive. As Sinkankas noted:
The original host rocks of the diamond crystals remain unknown despite much past speculation, “proof” of host rock sources by some authorities, and modern intensive geologic exploration of the regions presently yielding diamonds. Brazilian diamonds are found in a sort of matrix to be sure, this being a conglomerate of well-rounded pebbles cemented together with sand and iron oxides.
In 1733, Portuguese authorities began granting royal licenses to individuals to work portions of the diamond deposits. Guarded mule trains transported the diamonds along the Estrada Real to Parati and Rio de Janeiro. This licensing system eventually broke down, as bands of runaway slaves and garimpeiros clandestinely worked the areas or stole the recovered diamonds. In 1772, the government abandoned this system and took full control of the workings around Diamantina.
The English mineralogist John Mawe is probably the most celebrated European traveler to Brazil’s interior, having been the first foreigner to reach the diamond mines. In 1809 he received approval and funding from the Portuguese crown for his visit. His descriptions of the diamond region are still some of the most detailed. A vivid portrayal of the washing plants and the diamond discovery methods emerges in his 1812 account, Travels in the Interior of Brazil:
A shed is erected in the form of a parallelogram…consisting of upright posts which support a roof thatched with long grass. Down the middle of the area of this shed a current of water is conveyed through a canal covered with strong planks, on which the cascalhão