The Golconda Diamonds are diamonds from India from the geographic area in the Telangana and Andhra Pradesh States of South India. During the rule of the historic Qutb Shahi Dynasty (16th to 17th Century CE), which is also known as the “Golconda Sultanate” diamonds from the mines, especially the Kollur Mine were transported to the city of Hyderabad to be cut, polished, evaluated and sold.
Hence, Golconda in Hyderabad established itself as a diamond trading centre, and until the end of the 19th century, the Golconda market was the primary source of the finest and one of the largest diamonds in the world.
Golconda diamonds have a high degree of transparency, a quality that is rarely seen in diamonds from other areas. The special whiteness about them is often described as soft, limpid, watery or crystal clear. This whiteness should not be confused with the color grade or clarity, rather this is the quality in which light appears to pass through the stone as it if was totally unimpeded, giving the stone its soft appearance.
Famous diamonds that came from the Golconda mines are: The Blue Hope Diamond, Dresden Green Diamond, Daria-i-Noor Diamond, the Regent Diamond, the Koh-i-Noor Diamond, the Orlov Diamond and a few smaller stones.
Famous diamonds from the Golconda mines have their cut and shape as indicative that these stones are from there. Typically they are brilliant cushion cut, oval, pear marquise or other unique shapes.
Another possible identifying characteristic of Golconda diamonds tend to be Type IIa diamonds, as this type of diamonds are rare and probably less than two percent of all diamonds in the world fall into this category. Type IIa diamonds have no measureable nitrogen or boron impurities and because they are so pure, they transmit UV and visible light that are blocked by Type I diamonds. Colorless Type IIa diamonds are exceptionally transparent.
Colored diamonds like pink can be Type I or Type IIa. However, the majority of blue diamonds are Type IIb and are nitrogen free and their blue color is due to traces of boron.