From Mr Streeter we learn that in commercial estimation, coloured gems stand far behind the diamond; insomuch, he tells us, that this stone represents ninety per cent., and the others altogether only ten per cent. of the quantity on sale. A hundred years ago, Brazil became the rival of India in the production of diamonds, and the finders were the poor mulattos and negroes, who explored for them the sterile wilds of Minas-Novas, and sold them to the merchants. The story of the discovery of these gems at Bahia is as follows: A slave who came from Minas-Geräes was tending his master's flocks in Bahia, and he noticed that the soil resembled that of his native place. He groped in the sand and found seven hundred carats of diamonds. He ran away, and offered the gems for sale in a distant city. Of course such wealth in the hands of a slave aroused suspicion, and the negro was arrested and sent back to his master, who tried in vain to come at a knowledge of his secret. At last he bethought him of sending the slave again to tend his flocks at Bahia, and he watched him. Again the slave-shepherd groped in the gem-hiding sand, and the truth was discovered. Then came numbers of wealth-seekers from Minas-Geräes and other parts of Brazil, so that the next year twenty-five thousand men were diamond-hunting in Bahia, and the amount daily obtained for some time rose to one thousand four hundred and fifty carats. The trade was a prerogative of the Portuguese crown, and Lisbon was the chief emporium of the gems. The precious things are of fluctuating value. In 1836 they were very dear; but in 1848 the price fell; and a few years ago there was 'a glut in the market,' in consequence of Dom Pedro's having paid the Brazilian state debt to England in diamonds instead of money, when the price fell fifty per cent. in the Leipsic market.