Golconda Type IIa diamond ring. Centrally set with a cushion shape old mine Golconda Type IIa diamond, D colour, IF clarity with an approximate weight of 2.09 carats in an open backclaw setting, further set with six eight cutdiamonds in open back grain settings with a combined weight of 0.06 carats. The total approximate diamond weight is 2.15 carats, to an elegant flanked solitaire design featuring millegrain edging, an intricately pierced gallery and open backholing, leading to slightly raised shoulders with chenier detail and flowing through to a solid D-shapeshank. Testedplatinum, English, circa 1910. The origin, type colour and clarity of this diamond make it one of the finest in the world. Accompanied by Gemological Institute of America (GIA) report #2201198977.
Diamonds are classified by scientists into two main types, depending on the presence of nitrogen in the diamond's chemical makeup. Type II diamonds contain little to no such impurities. This type is further subdivided into two groups, ‘a’ and ‘b’, both of which make up less than two percent of all gem quality diamonds. Type IIa diamonds are extremely rare, and the most pure of all diamonds, and consequently exhibit superior transparency. This type was first identified as coming out of India, namely the Golconda region. Some of the most famous diamonds in the world are Type IIa, including the Koh-i-noor and the Cullinan I.