"At the time of our journey about two thousand persons, of whom eight hundred were slaves, were engaged in this kind of work.
| Years. | Price of the oitava in assorted stones. | Number of oitavas found in the year. | Number of slaves employed. | Mean value of each slave. |
|---|---|---|---|---|
| 1817 | $20 | 600 | 1,500 | $125 |
| 1820 | 30 | 5 a 600 | 1,500 | 125 |
| 1825 | 30 | 5 a 600 | 1,500 | 125 |
| 1830 | 30 | 300 | 1,500 | 125 |
| 1834 | 60 | 300 | 1,500 | 125 |
| 1838 | 75 | 300 | 1,200 | 150 |
| 1840 | 100 | 250 | 900 | 200 |
| 1844 | 125 to 150 | 200 | 800 | 300 |
"In 1817 a stone of an oitava was sold for two hundred dollars.
"Gold is worth the following prices the oitava:
"In 1817, sixty-seven and one-half cents.
1820, sixty-seven and one-half cents.
1830, seventy-five cents.
1840, one dollar and sixty cents.
1844, one dollar and eighty cents.
"We see that the prices of diamonds and gold have advanced since 1817. This is owing to three causes:
"1st. The diminution of the number of African slaves, in consequence of the laws against the slave trade.
"2d. The diminution of the quantity found.
"3d. The celebrity which this rich locality has progressively acquired, and which attracts there many persons.