From a variety of causes the supply gradually diminished until about the year 1830, when the diminution was so great, coupled with the increased cost of exploration, that the rough stones cost eight dollars per karat. In 1843 the discovery of the Bahia mines increased greatly the yearly supply, which was then about thirty thousand karats. For two years after the discovery of the Sincora mines the supply amounted to six hundred thousand karats. But the great distance of the mines from the large towns and the coast, the fearful malaria which prevailed in the district, together with the difficulty of obtaining supplies, have prevented the working of the mines to any great extent; and in consequence the supply in 1852 sank to one hundred and thirty thousand karats. In 1732 the price of the rough gem was five dollars per karat, but in three years after it rose to about eight dollars per karat, and remained at that figure as late as 1742. The Brazilian diamonds are generally very small compared with those yielded by some of the India mines, like that of Gani, which produced a great many gems of ten to forty karats weight. Of the Brazilian yield it was found by Professor Tennant that out of one thousand diamonds, one half weighed less than half a karat; three hundred, less than one karat; eighty, one and a half karats; one hundred and nineteen varied from two to twenty karats, and only one reached twenty-four karats. Brazil still exports annually diamonds to the value of several millions of dollars, but the exploration has probably been checked by the influx from South Africa and the consequent fall in prices. Out of the immense number of gems yielded by these mines,--the district of Minas Geraes is said to have produced two tons in weight,--it is strange that more large gems have not been found. Quite a number of diamonds exceeding fifty karats have been discovered, and several over one hundred karats, the largest being known as the Star of the South, which weighed two hundred and fifty-four karats. This fine gem was found in 1853 in the mines of Begagem by a negress. It was in the form of a dodecahedral crystal. Another fine gem, called the Abaethe, was found in 1797 in the alluvium of the river Abaethe. Three convicts, banished into the interior of the savage country, wandered about from thicket to thicket and mountain to mountain, in hope of discovering some treasure that would restore them again to their friends. After six years of weary wanderings and severe privations they at length stumbled upon a diamond of one hundred and five karats in the bed of the river above named. They ventured to return to the inhabited regions and confided their good fortune to a priest. He took them at once to the Governor of Villa-Rica, who suspended the sentence of the convicts and sent the priest to Rio Janeiro with the gem.