[This information comes from the LAPADA website with their permission. You may read the entire unedited information on their website by clicking here.]
All jewellery should be handled with care as precious and semi-precious stones are easily chipped and diamonds can scratch other stones and metals. Always remove rings when washing or washing up as even tap water temperatures can shatter emeralds, sapphires and opals as well as other stones. Keep jewellery away from perfume sprays, hair lacquer and make-up as well as from strong sunlight and direct heat which can change the colour of turquoise and organic materials like pearls, coral, shell cameos and ivory. When wearing jewellery, make sure that it is securely fastened and consider having a safety chain or catch fitted to necklaces, bracelets and brooches. Ancient jewellery is often corroded and can break easily so it is advisable to check with a metal conservator that a piece is strong enough to wear. Ancient gold jewellery was usually made from almost 24- carat gold which is softer than modern gold and marks, scratches and bends very easily. It pays to check jewellery set with precious or semi-precious stones regularly with a magnifying glass to see that no stones are loose or missing. Make sure that clasps and catches are secure and that the claws holding stones are not pulled up or wearing away. It is easy to catch claws in clothing and pull them away. Costume jewellery 'stones' are often held in place with adhesive; check that it is still effective. Check the stringing of necklaces, looking for fraying, or sharp edges on beads. Check chains for wear at the end of the links, especially gold chains as gold, being much softer than silver, can wear surprisingly quickly if a piece is worn regularly. Pearl and bead necklaces should be professionally strung with knots between each pearl or bead, to prevent rubbing against each other and to guard against losing them all should the stringing break, unless the beads are very small, when it can look 'gappy'. It's a counsel of perfection to have necklaces restrung annually, but this should be done if worn constantly.Wearing pearls regularly improves their sheen which can be lost entirely if they are not worn for a long time.
Avoid mixing jewellery together in one box as the many different materials may scratch or chip each other. Purpose built jewellery boxes, cases and rolls are a good idea as they keep pieces apart. Chains and necklaces that are not worn often can be rolled diagonally across a sheet of acid-free tissue paper, a soft cloth or chamois leather and kept flat in a drawer. Never wrap jewellery in cotton wool. Silver jewellery should be kept in acid-free tissue paper or tarnish resistant cloth. Do not wrap it in baize, felt or chamois leather as they will tarnish the silver. Never let an elastic band near silver as it corrodes it.
Ancient jewellery, as well as rare or precious pieces, should only be professionally cleaned. Porous stones like opals, pearls and turquoise should not be washed or immersed in water as they lose their lustre, nor should they be kept in very dry conditions, bright light or heat.They can however, like tarnished metal jewellery, be buffed gently with a soft jeweller's cloth or wiped gently with a very slightly damp chamois leather. Pieces with stones in an enclosed setting should not be immersed in water as liquid may get trapped behind the stone. They can instead be cleaned with a soft, clean nap-free cloth dipped in clean pure alcohol then rinsed and dried with something similar. It is also best not to allow strung necklaces or bracelets to get wet as the thread will shrink and eventually rot but the beads can be cleaned with damp cotton buds. Cameo, intaglio and enamel jewellery and any pieces made from materials such as ivory or coral can also be cleaned with a handkerchief dampened in warm soapy water, but be careful not to allow ivory to get too wet.
Costume jewellery 'stones' can sometimes be stuck back into position with a quick-setting epoxy resin adhesive after removing all the old adhesive. Otherwise all jewellery repairs should only be carried out by a reputable jeweller or silversmith who has experience in dealing with old pieces.