Diamonds – or, to be fair, any exquisite bejewelled gifts - aren't always forever.

Owners of precious gemstones who suffer a break-in or robbery can be hit for six when they belatedly discover that they're inadequately insured; had no idea of the true worth of valuables in their home; or failed to take enough care to ensure their insurance would pay out – and so can lose their jewels for good.

Sadly, it often takes a high-profile robbery from a celebrity home to hammer this home.

Most recently showbiz couple Sharon and Ozzy Osbourne bore the financial brunt of a pernicious theft after it was revealed that a £2m robbery of rings from their house would not trigger an insurance payout as they hadn't locked them in their safe.

It remains the case that when it comes to priceless jewellery, cover is the absolute king – and ensuring your gemstones are safe is essential.

"More than 30 per cent of jewellery claims are affected by lack of cover."

If you haven't yet done so, one sure-fire way to be shaken into action is to get your jewellery valued.

Whether it's an inherited necklace, a wedding gift or treasured gem from your spouse or partner, it can be very easy to overlook their true worth and slip into complacency about insurance.

"People often make a claim for jewellery and are shocked to find that they are not covered for the full amount," says Christopher Milton Stevens, managing director for the Guild of Valuers and Jewellers (GVJ). "In fact, more than 30 per cent of jewellery claims are affected by insufficient insurance."

Worryingly, research from a UK high-street bank recently suggested that more than four in ten (42 per cent) of engagement rings are uninsured.

Most people will, understandably, have a general lack of knowledge about an item of jewellery's true value that leads to it being inadequately insured – but there are plenty of external factors to watch out for too.

"Gold inflation can exert real impact on your personal wealth – and shine the spotlight on the need for appropriate insurance."

Over the past few years, the stratospheric rise in the price of gold – more than 30 per cent over the past 12 months - to $990 per troy ounce, and silver to $21 per troy ounce will have had a particular impact on the value of much jewellery.

At those prices, for example, a solid gold brooch bought as a gift in late 1999 when gold nudged $250 an ounce could today be worth four times its original value.

Such inflation can exert real impact on your personal wealth – and shine the spotlight on the need for appropriate insurance, says Milton Stevens.

"Jewellery does not follow inflation like ordinary products. This has been clearly demonstrated recently by the huge rise in gold and platinum prices, which have moved by 40% this year alone," he stresses.

"In most cases, your valuation should be updated every three years, as having a professional valuation means that you can have values adjusted as the market moves."

Quite simply, a valuation will determine the market value of your jewellery and, in many cases, include an analysis of your gemstones' condition that can highlight any damage and prevent any further loss in value.

So what do you actually get as part of the valuation process?

A valuation from the GVJ, for example, first lays out a detailed description of each item; these will include your stone's measurements, all metal types included and its weight.

Next, and crucially, you'll receive the insurance replacement value – followed by colour images of each item valued. An insurer notice will then be handed to you to pass to your insurance company before your gemstones are then registered to a central database.

And you don't even have to leave your home: for larger collections, a valuer can even come to your house or, by checking with individual companies, there may be a valuation day in your town or area.

Putting your jewellery through a valuation also protects you when it comes to proving ownership of an item, Milton Stevens adds.

"The police recover millions of pounds worth of jewellery each year and are unable to identify the rightful owner," he says. "Likewise, arresting a thief relies on proving that items in their possession are not legally theirs – and without this proof, the police often have to let suspected criminals keep potentially stolen items as their own."

It's worth noting that valuations by the GVJ can be registered to a secure online database for added security. This can provide a limited view for the police allowing them to reunite recovered items of jewellery with the rightful owner.

You can find a valuer at either www.gvj.org.uk or alternatively, try the Association of Jewellery Appraisers at www.ajappraisers.org that lists specialists in your region.

You can expect to pay either per item or per hour of work, depending on the size of your jewellery collection, and the costs can start from £50 per valuation.

By Sam Dunn