The diamond-washing establishments in Brazil have recently been visited by the distinguished traveler J.J. von Tschudi. On his way thither he was invited to stay in the neighboring town, Serro, where considerable commerce is going on in this gem. Tschudi was not little surprised when he witnessed how unsuspectingly the dealers intrust their goods. At the request of a friend he was immediately furnished with over 570 carats, or about one quarter of a pound of diamonds, making a value of 21,400 rix dollars. One of the most remunerative washing establishments (Lavra) of Brazil is, according to Tschudi, that of San Joao de Barro. It is, however, not rich in stones of the first water, or those free from slightest faults, while diamonds of the second and third water are met with quite abundantly. Diamonds of the second water are called such, which exhibit spots, clouds, or flaws; but those having an undecided color, or that are injured by other material faults, are designated as being of the third water. The washing operation requires considerable skill. For an inexperienced eye it is exceedingly difficult to detect a small diamond among a mass of glittering quartz, talc, or micaceous schist. Tschudi, in spite of carefully searching, and although the gem lay on the top of the sand, was unable to find it. To the keen and well-practiced eye of the negro, however, not a diamond of the size of a pin's head remains unnoticed. Thequantity of gems collected per day amounts to from thirty-five to seventy carats, which is equal to about one hundred and fifty diamonds. The gems collected, from the beginning of the season up to the time of Tschudi's stay, weighed 2,700 carats, and consisted for the greater part of beautiful stones, some of which exhibited a greenish tint, which disappears in grinding. During the time when the washing establishments were under royal administration, every negro who found a diamond of seventeen and a half carats, received his entire freedom, and presents were awarded to those who found smaller ones. As to the etymology of the term carat, it is derived from the word Mara, the coral tree, the red pods of which, when dry, were formerly used for weighing gold dust. Four grains are equal to one carat, 151 carats being equal to one ounce troy weight. Dr. Lewis Feuchtwanger, in his treatise on gems, gives the following prices for diamonds in gold currency, viz.; 2 grains (half a carat), from...................% 68 to $75 3 " ............ " .................. 80 to 90 1 carat.............. " .................. 110 to 140 U carat (6 grains)............................ 200 2 " (8 " )............................ 400 3 " (12 " )............................1,200 to 1,400 4 " (16 " )...........................,l,60p to 2,000 6 (20 " )............................3,000 to 4,000 Diamonds differ considerably in their color. Forty per cent are in general colorless, thirty per cent may exhibit a slight tint, and as many may show a decided color. Aside from the limpid or colorless stones, those of a dull whitish or greenish tint are most common. In polishing them some of the colors disappear, when the diamonds will distinguish themselves by their pure water. Light shaded rough stones are therefore not always less valuable than limpid ones. Light-tinged diamonds are more common than deep-colored ones, blue and green are very rare, and bring exorbitant prices. Tschudi enumerates the following colors which diamonds exhibit: Citron and wine-yellow, brass, ocher, and brown-yellow, but not sulphur-yellow; fight-brown, pink, and red-brown ; rose, peach blossom, and cherry-red; green in all shades, as pale sea-green, leek color, pistachio olive, thistle-finch color, emerald and bluish green, greenish gray; light gray, ash gray, smoky gray, pure black and dirty black. Most colored stones are found in Rio da Bagagne, they also occur frequently in Sincora in the province of Bahia. The most refractory to the cut is the black diamond, such as used for the carbon tool points, which were described in our issue of July 24. It mostly occurs in the latter province, sometimes in pieces of from one to two pounds. One of the most extraordinary curiosities in the way of diamonds is a crystal inclosing a gold leaf. Dr. Nello Franca, who makes mention of this stone, asserts that the gold is seen as if not imbedded in the diamond at all. This peculiar specimen speaks against the hypothesis of those who consider this gem as having directly originated from carbon or carbonic acid.
This article was originally published with the title "The Diamonds of Brazil" in Scientific American 21, 10, 154 (September 1869)