Located between the two major sea ports of India, Surat and Machilipatnam, a thriving market developed at Golconda from the Kakatiya reign - renowned for the diamonds found in the south-east at Kollur Mine, near Kollur, Guntur district and at Paritala and Atkur in the Krishna district. At the time, India was the only country in the world that had diamond mines. Golconda, the fortress-city within the walls, was thus very famous for diamond trading and other gems sold there, which came from a number of mines.
The Golconda Fort was first built by the Kakatiyas on a 390 foot-high granite hill surrounded by strong battlements. The fort was rebuilt and strengthened by Rani Rudrama Devi and her successor Prataparudra. After a number of other rulers, it fell into the capable hands of the Qutb Shahis. Golconda slowly rose to prominence and over a period of 62 years, the mud fort was expanded by the first three Qutb Shahi sultans into the present structure - a massive structure of granite 5 km in circumference. It remained the capital of the Qutb Shahi dynasty until 1590 when the capital was shifted to Hyderabad. The Qutb Shahis also expanded the outer wall of the fort to 7 km enclosing the city. Finally, it was an eight-month siege by Mughal emperor Aurangzeb that led to its ruin in 1687.
Others include, Nassak Diamond (43.38 carats), Sancy (55.23 carats), Hope (67 carats), Dresden Green (41 carats), Princie (34.65 carats), Wittelsbach-Graff (31.06 carats), Noor-ul-Ain (60 carats),
The world's largest diamonds were discovered during this period at 'Kollur' and other mines in a specific geographic area - now present-day Telangana and Andhra Pradesh. The diamonds were transported to be cut, polished and after being evaluated, sold to the richest customers. The town developed as a trade centre and under the patronage of the Qutb Shahi rulers, a thriving market diamonds and other precious stones, developed near the Golconda Fort. Golconda was soon established as a diamond trading centre and became the main source of the finest and largest diamonds in the world. More than 100,000 workers were involved in diamond trading drawing travellers from all over the world. Needless to say, the rulers created all necessary facilities for these important businessmen particularly those from Europe and Central Asia.
Hyderabad remained a diamond trading centre until the end of the 19th century, with the Golconda market being the primary source of the finest and among the largest diamonds in the world. The Golconda region can be said to have produced some of the world's most famous diamonds, including the colourless Koh-i-Noor. Other famous Indian diamonds include the blue "Hope" diamond (United States), the pink "Daria-i-Noor" (Iran), the white "Regent" (France), the "Dresden Green" (Germany), the "Orlov" (Russia), "Nizam" and "Jacob" (India), as well as some diamonds that are now lost - the "Florentine Yellow", "Akbar Shah" and the "Great Mogul".
Early travellers to India have left their opinions about the rulers and the wealth of India. Among them was the renowned French traveller Jean-Baptiste Tavernier who was also a jeweller. He claims to have seen a flat diamond called the "Great Table diamond", which was kept in a dungeon in Golconda. Two other French travellers Jean de Thevenot and Francis Bernier were also there as traders of diamonds.
The Golconda Fort is known to have had a vault where the Koh-i-Noor and Hope diamonds were once stored along with other diamonds. By the 1880s, Golconda's name was being used generically by English speakers to refer to any source of great wealth. Gemologists are also known to use this classification to denote a diamond that has a complete lack of nitrogen in its composition. Also material connected with Golconda is referred to as "2A". During the Renaissance era, the name "Golconda" had acquired a legendary aura and became synonymous with vast wealth. The mines brought riches to the Qutb Shahis of the State of Hyderabad who ruled Golconda up till 1687. After them, the Nizam of Hyderabad ruled Hyderabad till the state's independence in 1724 from the Mughal empire, after the death of Aurangzeb. In 1948, the Hyderabad state integrated with India.