Pearl conch

There ate several other molluscs that can, on occasion, also produce pearls. The most mous are the conch and the baler, which both produce pearls of great value, althoi they are non-nacreous. Others, such as the horse conch and the noble pen shell, are less well known. Some molluscs produce concretions that are called pearls, but which tend to be curiosities rather than beautiful items. The most mous is the clam. 

Conch pearls are very rare, slightly oval in shape, and are seldom more than 8 millimetres long. Th have the same orange or pink... 

The baler, Mdb meHo, and other molluscs of the same genus, are also gastropods and can also produce pearls. The baler shell is orange inside and has the same flame pattern as a conch shell. The pearls can vary in size, some being quite large. They display the same colouring and flame pattern as the shell. 

Conch and baler pearls display a flame-like pattern when viewed under magnification (Fig. 9.9). This pattern appears over the surfiice of the whole pearl, finm every angle. The pattern would be missing from some areas in items fiishioned from the conch or baler shell itself. Instead there would be evidence of the banded structure of the carved shell (see Chapter 10, Shell ). 

Ultraviolet light. Some shells - for example, mother-of-pearl -fluoresce a chalky-white under UV light. In conch cameos the white area has a stronger fluorescence than the pink, and in helmet cameos the brown or orange layer can be inert. With the exception of casein, plastics are inert. 

In Europe shell jewellery consisted mostly of conch and helmet cameos, made into brooches, pendants, ear-rings and occasionally bracelets (though these would have been fragile). Mother-of-pearl from nacreous shells was also used, and could be intricately carved and fashioned into the same sort of items. Nacreous shells proved even more versatile than porcellaneous shells, because many of them were almost flat and therefore could be made into objects such as hair ornaments, fans, small boxes, gaming pieces and all sorts of trinkets (Fig. 10.23). 

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