Golconda is one of the most misused words in the diamond trade. It may refer to the historic Indian mining and trading region, a documented chain of provenance, or an opinion about a diamond's type and transparency. A careful description states which meaning is supported.

The historical source

India was the principal source of diamonds before deposits were discovered in Brazil in the early eighteenth century. The Golconda name became associated with mines and trade routes in southern India and with several historic diamonds.

Provenance requires evidence

An antique cut, colorless appearance or famous story does not prove geographic origin. Documents that place a diamond in India before other world sources entered the trade can support the attribution. Later stones may be compared with Golconda material without having Indian provenance.

Type IIa is a chemical classification

Type IIa diamonds show no measurable nitrogen or boron impurities in the infrared range used for diamond type classification. The category can include highly transparent stones, but Type IIa diamonds occur in deposits outside India. Type IIa status does not by itself establish Golconda origin, D color, flawless clarity or superior beauty.

Read the wording of an appendix or letter

A laboratory appendix may record an opinion that a diamond has properties associated with historic Golconda diamonds. Quote the document accurately and distinguish the laboratory's language from the seller's interpretation. The main grading report and any appendix should be reviewed together.

Judge the individual stone

Transparency, cut, color, clarity, condition and provenance all matter. None should be replaced by a single prestige label. Inspect the diamond beside its reports and in motion, then decide whether its face-up character supports the description and price.

Questions to ask

  • Is Golconda being claimed as geographic provenance, historical association or optical comparison?
  • Which document supports that wording?
  • Does the report identify the diamond as Type IIa?
  • Is the stone antique cut, later recut or modern cut?
  • Are ownership history and laboratory opinion being kept separate?

GIA's overview of Golconda diamonds discusses the historic region, documented history and diamond type. GIA's diamond type classification notes that Type IIa diamonds occur in multiple deposits, with Golconda as one historically important source.