This necklace, by the British jeweller and hardstone carver Charlotte de Syllas (born 1946) was commissioned by Malcolm MacEwen as a gift for his wife Ann to mark their Silver Wedding Anniversary in 1972.

It consists of alternating bands of white gold and black jade with, at the centre, two faces in profile carved from opal. The faces are not portraits but are intended to illustrate the balance of male and female in the natural world. The form of the central element was inspired by a sparrow hawk's skull, with a white gold beak protruding below, while the stripes of the necklace represent the wing feathers of the bird. Behind the two profiles and facing towards the wearer is a third face, carved in rock crystal and framed within a shaped border of white gold. Charlotte de Syllas has explained that this face is that of a mystic - of one who has banished or is trying to banish all thought. The clasp brings together two sculpted hands clenched around a baton.

Malcolm MacEwen was a journalist, while Ann was a distinguished town planner who had worked on the post-war redevelopment of London's East End and on pioneering urban traffic schemes. They are remembered also as champions of Britain's National Parks for which they campaigned and wrote after their retirement.

According to Charlotte De Syllas their wish was for a restrained rather than a flamboyant piece - a necklace that could be worn for a business lunch. Ann's well-cut tweed suits encouraged De Syllas to hunt for a brown jade but she found instead this Edward Black jade from Wyoming, a stone which she found a delight to carve due to its very smooth structure. The two faces are carved from the same block of opal, but contrasting flashes of colour were achieved by cutting it in half and turning one upside down. Thus the female has predominantly green lights and the male predominantly blue.

This is Charlotte de Syllas's first major necklace and the first piece in which she moved from setting a carved stone into a piece of metal jewellery, to creating the form itself from elements of stone pieced together. With its elegant minimalism, its commanding figurative elements and its subtle evocation of the sparrow hawk, it is a superbly balanced piece and a fine demonstration of the technical perfection which underlies the fluidity of her work.