Know your silver
You never know what to expect when called out to provide a house contents valuation. A friend of mine, who was valuing the silver collection in a grand house in East Anglia, came across an 18th-century Irish dish ring in the basement. Such rings were used to support hot plates, and this was a fine example with rococo decoration and worth about £6,000.

A closer look revealed an engraved crest on the dish ring. To my friend's astonishment the crest was that of his own mother's family and not that of the present owners. Knowing that his mother's family silver had all been stolen in the 19th century, he felt obliged to inform his pursed-lipped client that she was in the possession of stolen goods.

After a sharp intake of breath she explained that it had been given to her as a wedding present. No accusations of theft were made and by the end of the day a deal was struck. The silver dish ring now takes pride of place on my friend's dining table.

Most experts will be able to tell the difference between solid silver and silver plate just by handling the item. But there are several clues for the uninitiated. To keep its shine, silver needs to be polished regularly and frequent cleaning can wear away small areas of plating, showing the base metal below - this kind of show-through is known as bleeding.

Look out for hallmarks. By law British silver must be 92.5 per cent pure. Assay offices around the country check the purity and mark each piece that is passed. In Britain there are three standard marks indicating that a piece is made from sterling silver. A lion passant represents English silver, a crowned harp Irish silver, and a thistle or lion rampant Scottish silver. Likewise, the assay offices themselves are represented by particular marks: London by a leopard's head, Sheffield by a crown, Birmingham by an anchor and Edinburgh by a castle.

The various assay offices also use letters of the alphabet to indicate the date of the piece, but over the centuries the system has become enormously complicated and even the most learned of silver experts will carry a pocket hallmark identification book. Some items of silver may have additional initials before the hallmark, representing the maker. Depending on the maker's importance, these marks can often add value. A copy of Jackson's Silver and Gold Marks of England, Scotland and Ireland will identify most marks.

Scottish regional silver is very collectable at the moment; there is not a great deal of it about and when it does come on to the market it is fiercely competed for. Pairs of Georgian silver candlesticks and Georgian silver tea pots are always desirable.