Published online by Cambridge University Press: 28 February 2012
Pinctada margaritifera mollusc iscultivated in French Polynesia for the production of black pearls.For this study, the colour of juvenile samples (48 days old) wasinvestigated in the visible range spectra (430–700 nm) using spectrophotometry.A first measurement was done with the soft parts still inside theshell (entire animal). Then, the soft parts were removed in orderto do a second measurement on the growing edge of the shell. Comparisonof the two measurements shows that the estimation of the livinganimal colour with unaided eye is strongly influenced by the colourof the soft parts. The use of the International Commission on Illumination(ISI) chromaticity diagram shows that at this growth stage, theshells are “white”; i.e. present no absorptions to the visible part.Multivariate statistical analyses based on the intensities of 6 wavelengthsshow that the shell colour is less variable than the colours ofthe entire animals. Wavelength intensities of the shells are similar,so no colour trend is visible. On the other hand, the colours ofthe entire animals are darker, and more variable. At this growthstage, the shell colour is not predictable for a potential selectionof receiver or donor.