Leisure hours among the gems

by Augustus C. Hamlin

Borneo is thought to be rich in diamonds, but concerning the extent and productiveness of the placers but little definitely is known. The island has long been known as abounding in the gem, but travellers and mineralogists have been prevented from exploring it by a variety of causes, chiefly arising from opposition of the native rulers and difficulty in penetrating into the interior of the country where the mines are found.

Tavernier was desirous of visiting these mines, but was dissuaded from going by these supposed or fancied difficulties, and the fact that the Queen at that time forbade the exportation of the gem. Therefore we have to regret the absence of the report which this able and truthful traveller would have made if he had visited those regions.

The Borneo diamonds are reported to be the best in the world, and to owe their excellence to a faint steel-like tinge and a very vivid adamantine flash. We are inclined to think, however, that diamonds of this description may be found in various countries, and that commerce assigns their locality to Borneo as a matter of convenience and trade.

Borneo is yet a terra incognita, and its features have not yet been made known to geography or even commerce. The second island in size in the world, and itself almost a continent, it presents a vast field to the explorer, with its broad prairies, immeasurable forests, deep and impenetrable jungles, interspersed with lofty ridges of mountains. Its mineral wealth is undetermined, but enough is known to found the belief that the island is one of the richest in this respect on the globe.

Concerning the diamond mines we have but imperfect accounts and none of very recent dates. However, it is known that the character of the mines is the same as that of India and elsewhere, and that the gems are found in a gravelly stratum at various depths below the surface. The best of these mines are said to be situated along the river Lavi, near Sukkademia, and to be worked in a rude manner by the Malays and Chinese. Mines on the northwest coast of the island have been worked extensively, but it is reported that no large diamonds have been discovered there. The Colonial Secretary, Mr. Low, states that the gems are found in the greatest quantities in Sango, Landak, and Banjarmassin, and that the stones, although of small size, are of the purest water.

The quantity of diamonds afforded by Borneo is not exactly known, but a recent writer in the Journal of the Geographical Society of London gives it as about two thousand karats annually. It is also stated by various authorities that the mines of the island have never yet yielded a diamond of thirty-six karats in weight.

If these reports are correct, how can we explain the accounts of the great diamond belonging to the Sultan of Mattan, which may be found in the History of Java, by Sir Stamford Raffles, and also in the Memoirs of the Batavian Society?

The famous mines of Brazil, which gave rise to a new era in the commerce and history of diamonds, were discovered by accident. And we are not aware of an instance of the discovery of a single diamond district or region of country, with the exception of the Urals, which can be ascribed to the results of scientific research. Even the wonderfully rich mines of the Province of Bahia in Brazil were first made known by a slave who noticed the similarity of the soil to that of the diamond mines of Minas Geraes, where he had formerly worked.

In 1727 a Portuguese by the name of Lobo, while visiting the gold mines of the Sierra do Frio, a desolate country about four hundred miles north of Rio Janeiro, noticed some bright crystals of stone which the ignorant miners picked up from time to time and treasured as trifles. Gathering a number of them, he submitted them to some Dutch traders, who informed him as to their valuable character. The Dutch at once contracted with the Brazilian Government for all of the rough diamonds that might be found, and for a long time controlled the trade. The mines where the gems were first discovered were situated in the midst of a desolate country destitute of vegetation and of considerable elevation above the level of the sea. Since this period other mining districts have been discovered, and it is now ascertained that the whole of the vast territory situated between the twelfth and twentieth parallels of latitude and extending even to Matto Grosso, a thousand miles distant, belongs to the gem-bearing formation.

This vast space of territory has not been examined scientifically, and but little is known of its condition except that it is diamond yielding. Since their discovery the mines have been worked with more or less activity with slave labor under the direction of companies of large capital. Skilled labor with the modern appliances of science has not yet been employed in these mining districts. And the condition of the country, its laws, and the controlling power of the diamond corporations, will render the application of scientific skill a difficult and hazardous task. The explorations are conducted in a primitive manner during the dry season, which lasts from April to October. They are made generally in the beds of the streams which have been dried up by the summer’s drouth. Rivers are sometimes diverted from their natural course, and their gravelly beds completely removed to sheds on the banks to await the rainy season, when water, which is required for washing, will be in abundance. The cascalho, a name given to the peculiar gravel, composed of quartz fragments mixed with sand and clay united with a ferruginous cement, which contains the diamonds, is then placed in shallow troughs, and a stream of water directed upon it until it is well cleansed, when it is removed and dried in the sun. The dried residue is then carefully searched for diamonds, and it is not always easy to distinguish them among a great variety of pebbles, of which the débris is chiefly composed.