Expertly cast sterling silver Cockle shell necklace.
The original shells used in the creation of Soham's jewellery have been found at Fremantle's popular South Beach.
The method used to create a silver replica of these shells is called "lost wax casting" and the process has been used for thousands of years.
The caster starts off with the original shell which is put into a cold mould that is made up of two parts. The mould is then split and the original shell taken out. The two halves are put back together and wax is injected into it. This leaves you with the original pattern of the shell but made out of wax. This wax pattern is then put into a flask which is filled with investment plaster. Once the plaster has set, the flask is put into an oven where the wax is burnt out before cooling.
The flask is placed in a vacuum casting machine, molten metal is poured into a hole in the top of the investment and sucked through, filling the space in the plaster left from the wax shell. Once the metal has cooled down the investment plaster can be washed away and you are left with the original pattern in metal.
The cast metal object can then be polished, filed and made into jewellery.
The original cold mould of the shell can be reused to produce wax castings so that multiples can be made.