Explanatory notes
… molluscs (especially of the pearl oyster and the pearl mussel). Pearls have a shiny surface and consist essentially … may be shaded or coloured (e.g., grey, black, purple, red, yellow, green or blue). They are usually round, but … or cultured pearls whether unworked, i.e., as gathered and merely cleansed (for example, by means of salt and water), …
