D I A M O N D S

Until the discovery of the Brazilian deposits in 1728, the supply of the whole world was derived almost entirely from the Indian sources, Borneo, Southeast Asia island, being at that time the only other known locality.

The occurrences of diamond in India were distributed over an extensive area of the country.
C. Ritter in his Erdkunde von Asien (vol. iv, part 2, p. 343, 1836) collected together the various scattered reports concerning the diamond localities, and was the first to give a detailed and connected account. Later (1881), Professor V. Ball has given an exhaustive account.

That the occurrence of diamonds in India is almost entirely confined to the eastern side of the Deccan plateau is to be gathered from the finds of the present day and from the reports of earlier times. The southern boundary of the region in which diamonds have been found is the river Penner in latitude 14º N.; from this river the diamond localities form a frequently interrupted line running northwards on the east side of the Deccan plateau, crossing the Kistna, Godavari and Mahanadi rivers, and reaching the southern tributaries of the Lower Ganges in Bengal, between the rivers Son and Khan, in latitude 25º N.

Any other diamond localities outside the area just marked out are unimportant, and the reports concerning them are often uncertain. In general, many of the reported localities for diamond are doubtful, they're being no exact and reliable information respecting them, or they are simply based on the existence of old mines.

It is often supposed that all Indian diamond mines are of the greatest antiquity. In many cases the date at which the workings were commenced is not known; but the working of the most important deposits known at the present day does not date back to very remote periods, probably in all cases subsequent to the year 1000 A.D. and sometimes much later. Of a few mines it is known exactly when work began, as will be mentioned below.

Diamonds are found in India in compact sandstones and conglomerates, in the loose, incoherent weathered products of these rocks at places where they lie on the surface, and in the sands and gravels of those rivers and streams which have flowed over the diamantiferous strata or their weathered debris and have washed out the stones from their former situations.