寻宝

Have you misplaced your wedding ring? And what's happened to that gold necklace - a family heirloom you were wearing until... well, until you noticed it wasn't there anymore? Don't despair - try your luck with The Ring Finders. This online directory comprises more than 250 metal detectorists and is the brainchild of Chris Turner, who lives in Canada. It was created in 2009 and, according to Turner, has helped people to retrieve more than 1,500 pieces of lost jewellery.

Despite finding so much treasure, many metal detectorists don't do it for the money. In return for finding lost valuables, many only ask for a contribution towards their expenses, and perhaps a donation to their favourite charity.

That's because, for many people, walking around beaches and fields with these devices that squeak when close to metal is simply a hobby. One such hobbyist is Richard Higham, who works as a flying instructor, but in his spare time sweeps the ground, keen to find relics from the past. Once he found a copper coin, made between 160 and 260AD and stamped with a Roman Emperor's head. Richard was excited to think he was the first person in about 1,800 years to hold that coin in his hand.

It's a common belief that metal detectors are a relatively new invention - but in fact they've been around since the days of Alexander Graham Bell, who designed one in 1881. They work by creating an electromagnetic field which is transmitted into the ground. Any metal coming into contact with it creates its own field, and the detector picks it up.

For the past 17 years, the British Museum has run a Portable Antiquities Scheme, which keeps records of amateur finds around the UK. So far, it has recorded one million finds.

But what if you don't find your ring or your necklace? You can always console yourself with the thought that one day - maybe years from now - it could make a metal detectorist very excited. After this heart-warming thought, you might decide to give up the search and just call the insurance company.