Andhra Pradesh — A Diamond Heartland of South India
Andhra Pradesh — A Diamond Heartland of South India
The state encompassing Golconda, the historical source of many of the world's most storied diamonds
Andhra Pradesh, the state on the eastern coast of southern India along the Bay of Bengal, occupies a place in the history of the diamond trade that few political units anywhere can match. The diamond gravels and conglomerates of the Krishna and Penner river basins, falling within the boundaries of present-day Andhra Pradesh and the recently bifurcated Telangana, were for nearly two thousand years the world's primary source of gem diamonds. Until the eighteenth-century discovery of Brazilian deposits and the late-nineteenth-century discovery of South African pipes, virtually every important diamond known to history came from these workings — most famously from Golconda, the trade name for the kingdom and bazaar through which the gems passed.
Geological setting
The diamonds of Andhra Pradesh derive from a complex of kimberlite and lamproite pipes intruding the Eastern Dharwar Craton in the Wajrakarur and Narayanpet kimberlite fields, with secondary alluvial concentration in the gravels of the Krishna, Tungabhadra, and Penner rivers and their tributaries. The pipes are of Cretaceous age, and the bulk of historic diamond recovery was alluvial rather than direct pipe extraction. The Kollur mine on the south bank of the Krishna river, near present-day Guntur district, was the most productive single locality during the medieval and early-modern periods.
Golconda
Golconda was the fortified city and trading centre, in present-day Telangana, through which the diamonds of the region were marketed. The kingdom of Golconda controlled the trade from the fourteenth century until its absorption into the Mughal empire in 1687, after which the Mughals continued to source the most important imperial stones from the same mines. Golconda, in modern trade usage, is shorthand both for the geographic source and for a particular quality of diamond historically associated with that source: stones of exceptional transparency, generally of Type IIa designation, with a distinct character of colourless purity.
The mines yielded virtually all of the most important historical diamonds, including the Koh-i-Noor, the Hope (Tavernier Blue), the Regent, the Orloff, the Darya-i-Noor, the Nizam, the Great Mogul, and the Princie. Jean-Baptiste Tavernier, the seventeenth-century French traveller and merchant, visited the Indian mines six times between 1638 and 1668 and recorded the workings, the methods, and the social organisation of the trade in his published account, which remains a primary source.
Decline of historical mining
By the eighteenth century the alluvial deposits had been heavily worked. The Brazilian discoveries of the 1720s gradually displaced India as the primary world source for new rough, although the Indian mines continued to yield occasional important stones. The South African discoveries of the late 1860s ended India's role as a major producer of newly-mined diamonds.
The historical mines and their workings have been the subject of recent academic and field research. The Government of India and various state agencies have studied the kimberlite fields with modern exploration methods, and small-scale recovery continues at some of the historical sites, but Andhra Pradesh and Telangana are not significant producers of new diamond rough at present.
The Golconda designation in modern trade
Modern auction catalogues use Golconda as a quality designation rather than a strict origin attribution. A Type IIa diamond with the characteristic limpid transparency historically associated with the Indian mines may be described as Golconda type, although laboratory reports cannot prove a stone's seventeenth-century provenance from a particular mine. The premium attached to documented Golconda-period stones at auction reflects this combination of historical romance and the genuine optical quality of the originals.
Other gem material
Beyond diamonds, Andhra Pradesh has produced beryl, garnet, and quartz from various pegmatitic and metamorphic occurrences, although none of these has had the historical importance of the diamond trade.
In the trade
For dealers and collectors, Andhra Pradesh and Telangana are the geological homeland of historical diamond. The Golconda trade, the Kollur mines, and the Tavernier accounts together constitute the foundational chapter of the world diamond business. Modern Indian diamond manufacturing, centred in Surat and Mumbai, is conducted on rough imported principally from Africa and Russia, but the centre of gravity of the world's cutting trade returning to India after a four-century displacement carries its own historical resonance.