"At present the vintem of diamonds in very small pieces is worth in commerce from four and a half to five dollars. A stone of a demi-oitava would be worth now from two to three hundred dollars, according to its beauty. A stone of an oitava would be worth seven hundred and fifty dollars.
"Two or three years ago a stone of three-quarters of an oitava was sold at four hundred dollars, and another of the same weight for five hundred.
"Now there is scarcely found more than two hundred oitavas of diamonds per annum, and only two or three stones of a demi-oitava and above.
"The richest man of Diamantino had in his possession, at the time of our journey, two hundred oitavas of diamonds.
"The slaves sell the diamonds they steal at two, and two and a half dollars the vintem; large and small, indifferently.
"To recapitulate. After the researches which I made at the places, it appears to me probable that the quantity of diamonds extracted from Diamantino and from Matto Grosso amounts, since the discovery by the Paulistas to the present time, (1849,) to about sixty-six thousand oitavas; it must be remembered that in this sum are included a great number of large stones.
"In estimating the mean value of the oitava at one hundred and twenty-five dollars, we arrive at a total of about eight million two hundred and fifty thousand dollars. It is proper to add to this sum that of the diamonds taken from the basin of the river Claro. Although this last yields inconsiderably at present, and may be far from what it was under the Portuguese government, I cannot estimate it at less than fourteen thousand oitavas, worth about one million seven hundred and fifty thousand dollars.
"Thus the amount of diamonds drawn to the present time from the province of Matto Grosso will amount to about eighty thousand oitavas, worth ten millions of dollars.
"I do not doubt that this region may one day furnish, if it is submitted to a well-conducted exploration, an infinitely larger quantity. Unfortunately, as we have already said, the search for these stones is accompanied with great danger; and I am convinced that these baubles of human vanity have already cost, to Brazil alone, the life of more than a hundred thousand human beings."
M. Castelnau has given the value of diamonds and gold in the Portuguese currency of reis, and occasionally in francs. In turning the reis into dollars, I have estimated the dollar at two thousand reis. When I left Brazil, the Spanish dollar was worth nineteen hundred and twenty reis, and the Mexican eighteen hundred: so that my values are under the mark; but there is probably less error in this than in any estimate that Castelnau could form from his data.