Glittering prizes and watertight security

and look at the special precautions you'll need to take for expensive jewels

"Common street muggings have been a particular problem during the last two years. So has the practice of stopping cars in jams ... both are side effects of the greater levels of security in homes."

This is a warning from Ronald Mumford, the chief executive of TH March & Co, a leading specialist jewellery broker, that many thousands of people may be inadequately insured.

Even those with the most mundane of jewellery collections are unlikely to be insured against such thefts under the basic terms of their household contents policy. Normally, this will only cover against fire and theft while items are in the home.

Taking out an "all-risks" extension for personal possessions as a whole can, however, provide cover against theft or accidental loss or damage worldwide, subject to reasonable discretion being exercised.

Its cost will vary according to the postcode area. At Eagle Star, for example, rates range from pounds 1.15 per pounds 100 of insurance a year in a country area to pounds 3.85 per pounds 100 in the centre of London or Liverpool.

Pieces of jewellery worth more than a certain limit (often pounds 1,000) normally have to be specified by the policyholder. Those worth over a slightly higher threshold (typically pounds l,500) may require a valuation. Frequently this will cost around 1 per cent of the value of the item concerned.

Once collections start being worth in the region of pounds 20,000 to pounds 30,000, insurers are likely to insist on the presence of suitable safes and alarms as well as good perimeter security.

Anyone with jewellery in this range is likely to be better off with "high net worth" specialists than with standard household insurers. Their policies tend to be more flexible and their rates are usually more attractive.

Hiscox Underwriting's jewellery rates, for example, start at 50p per pounds 100 insured worldwide for specified items. For jewellery kept in a safe they go as low as 30p per pounds 100, and for that held in a bank as low as 0.12p per pounds 100. Hiscox is unusual in allowing a certain proportion of jewellery to be kept outside a safe at any one time (and thus be available for wearing) without the policyholder constantly having to give prior notice. It is also notable for offering the option of having claims settled in cash. Most insurers will normally only offer a replacement item.

The high net worth specialists commonly insure jewellery schedules of several hundred thousand pounds and deal with some cases worth over a million.

Some brokers refer to cases on their books worth as much as pounds 20m. Their clients' collections spend most of their time in bank safes but provision is negotiated for items to be withdrawn for wearing on special occasions and holidays. Such withdrawals will usually be limited to around a dozen days a year.

The requirements of insurers also strongly influence the heavy security measures used by shops. Commercial insurers will normally require grilles or laminated glass to protect against forcible entry, and good- quality safes and alarms throughout the premises.

Alarm systems in shops are sometimes fitted with a duress warning system. If they fail to be opened or closed using a particular sequence, a silent alarm is triggered which an intruder will not notice.

Jewellery shop raiders are often highly organised gangs; hold-ups can last just seconds and even manufacturers' and wholesalers' representatives are singled out.

An increasingly popular method of robbery has been for armed gangs to go to a jeweller's home and take him back to the shop while holding his family hostage. In such a situation he will obviously be reluctant to trigger any secret alarms.

Most jewellers have high-tech security in the form of closed-circuit television. However, some hold-up gangs have proved increasingly capable of spotting cameras and demanding that film is handed over to get rid of video evidence. Nevertheless, minuscule cameras the size of a keyhole are helping to reduce this problem. Cameras are also increasingly being based at other nearby locations.

What is more, there is some hope on the horizon for those with expensive items of jewellery, whether individuals or shops. Appraiser, a computer program developed by IBM, which should be up and running by the end of the year, will identify individual items of jewellery by the use of unique "gemprints" and by details recorded by a digital camera.

The police will be able to check recovered items against the Appraiser database.