Color Classification and Stability of Queen Conch Pearls by GIA

Interesting article from GIA about conch pearls.

Due to the ever increasing popularity and value of Queen conch (Lobatus gigas, formerly Strombus gigas) pearls, GIA has seen a steady increase in the number of conch pearls submitted to its various laboratories for identification. In response, this is an appropriate time to improve and expand upon GIA’s conch pearl color terminology in general and, more specifically, how it is applied to GIA Pearl Identification Reports.

To that end, GIA has redefined its approach to conch pearl color, so that it bears a stronger resemblance to the more refined process applied to GIA’s classification of nacreous pearls. Establishing and defining practical color boundaries has improved specificity and consistency in the description of conch pearl color opinions between all GIA gemologists and laboratories. In addition, the resulting conch pearl color classification system provides more precision in the communication of conch pearl color, for both the pearl industry and the public at large.

In order to be identified as Queen conch pearl, non-nacreous pearls that formed in the Lobatus gigas mollusk must fall into the red (pink) hues, namely reddish purple (extremely rare), purplish red, red, orangy red, and reddish orange. While conch pearls do occur in colors outside of this hue range, it is challenging to definitively identify them as such in a laboratory when they lack any red (pink) hue. Because the vast majority of Queen conch pearls fall into mid-tone and mid-saturation ranges, in the straight red hue, GIA (in keeping with the trade) has traditionally described conch pearl color in a much more general way than nacreous pearl color. The bulk of conch pearls were simply described as pink, unless the tone and saturation were significantly out of the mid-range in either direction (weaker or stronger). GIA’s current and historical data, as well as the studied sample materials, produced results that reinforced the notion that pink occurred most often, followed by Strong pink, Light pink, and Very light pink, with Red occurring very rarely.

Read entire article here: https://www.gia.edu/gia-…/queen-conch-pearls-color-stability