Pigeon blood, issued in Jaipur: GSI brings the trade names home

§1A name that had to be granted abroad, granted at home.

A ruby cut in Jaipur can now be called pigeon blood in Jaipur. Gemological Science International has begun issuing coloured stone reports carrying the recognised colour trade names, Rapaport reported on 19 August: Pigeon Blood for ruby, Royal Blue and Padparadscha for sapphire. The reports are available from the laboratory's Jaipur, Mumbai, New York and Bangkok operations. It is the first time such reports have been issued in India.

§2Old language, real money.

The names are much older than the reports. Pigeon blood and royal blue have been trade language for generations and laboratory language since the 1990s, and they carry real money: a stone that qualifies sells at a premium to one that does not, on a judgement about colour that a buyer cannot make from a photograph. Until now a stone finished in Jaipur had to travel to a laboratory abroad to be given one. Meenu Brijesh Vyas, GSI's global head gemologist, said of the change: That ends today.

§3Hue, tone, saturation, and one hard condition.

The criteria behind the names are not impressionistic. GSI defines each by specified ranges of hue, tone and saturation, assessed under standardised lighting and supported by spectroscopic and colorimetric analysis, and grants the designations only to untreated stones. Heated, diffused or otherwise enhanced material is not eligible whatever its colour. That last condition does most of the work, because heat is the commonest treatment in both ruby and sapphire and much the cheapest route to a colour that looks like the name.

§4How it compares with what Switzerland publishes.

The conditions sit close to what the Swiss laboratories already publish. SSEF requires of pigeon blood red a strong, vivid red saturation with no or only slight purplish tint, strong ultraviolet fluorescence from high chromium and low iron, no colour zoning seen from above, freedom from eye-visible dark inclusions and no fissure or cavity filling. Its royal blue requires strong, vivid blue without greenish, greyish or purple tint, a spectrum dominated by iron-titanium charge transfer, colour homogeneity and good transparency. SSEF applies pigeon blood red only to rubies showing no indication of any treatment. Another laboratory issuing on comparable terms in the city that cuts the stones changes where the judgement happens, not what the judgement is.