The diamond mines in Brazil, have at different times brought in different sums to the Portugueze government. Towards the middle of the last century such great quantities of the Brazil diamonds came to Europe; that the value of diamonds of every description was so much decreased, that the London jewellers refused to buy them at any price. The author of the _Treatise on Diamonds_ seems to doubt the existence of the diamond mines in Brazil, and to believe that the great profusion of those stones sold by the Portugueze in the different markets of Europe, were not the produce of their American, but Asiatic colonies. It will be easy to judge of the amount of the profit arising to the Portugueze government, during several years, from the sale of these diamonds, by the following statement. At the epoch of the dreadful earthquake in Lisbon; some English merchants had a contract with those Portugueze who had the direct management of the diamond mines in Brazil, to pay them 120,000l. sterling. The principal conditions of the above contract (according to the account given me by an English gentleman who signed it) were as follows:--the Portugueze directors engaged to secure to the English merchants the exclusive sale of the Brazil diamonds; the latter engaged on their part to take 40,000 carats of rough diamonds, for which they were to pay at the rate of 3l. a carat; making the sum total of 120,000l. sterling. An agreement was also made relative to the purchase and choice of the diamonds. On the cases which contained them being brought from Brazil, they were not to be opened but in presence of the English merchants, which being done, the diamonds were spread on a large table; and a person skilled in precious stones being appointed by the said merchants, he made choice of the most valuable diamonds, excepting those above twenty carats (very few in number), which were reserved for the crown of Portugal. The original contractors being succeeded by others, the price was reduced to 2l. 1s. 8d. sterling a carat; but for some time past this branch of trade has been taken out of the hands of the English, and is in the exclusive possession of the king. The exact sum resulting from this new arrangement is not known, but we have reason to believe it amounts on an average to about 60,000l. sterling, annully. _An Estimate of the Value of Brazil Diamonds_, &c. The white diamonds of Brazil when they weigh only from four to five carats, are of equal value with the Oriental ones of the same weight; but when of a larger size, the latter are much more esteemed, on account of the fineness of the water.