Did you hear the story of the couple in the UK who bought a costume ring for £10, wore it for 30 years thinking it was paste only to discover that the stone is in fact a 26.27-carat, cushion-shaped, white diamond, estimated value £350,000?

This isn't the only time this has happened - the internet is littered with anecdotes of children playing with grandma's costume jewellery only for the family to find out it was all real. Have you got some old jewellery that you've always thought was costume?

Look Closely

Are there any marks, is the piece signed? Metal has only been hallmarked in the past.

Try to gather as much information as possible as to where the piece came from. Look for original receipts, fitted cases, letters or notes giving an idea of where it was purchased, when and by whom.

Look for marks

Check the jewellery to see if it has any marks. Is it signed? Does it have a hallmark?

Diamonds

Antique diamonds were cut differently to what we see today. They may be bigger, this is because cutters used to cut with the shape of the crystal rather than cutting it down to achieve maximum sparkle that we want today. The old style of cutting didn't always show the brilliance of the diamond so they may appear slightly duller.

Coloured stones

Is there a coloured stone? Prior to 1950 coloured gemstones such as rubies, sapphires and emeralds were very popular - and seeing how much these gemstones are selling for today, with demand rising by the minute, it's more than worth a second look if you have a coloured gemstone in your old jewellery.

Give them a gentle clean and check for strong, bright colours and good transparency.

Is it unusual?

If a jewel looks highly unusual it might well be a unique, one of a kind piece and therefore carries a premium. It could be by an artist jeweller, a craftsman who did not work for a big jewellery organisation.

Look at the workmanship

Turn the ring over - what does it look like from every angle and underneath. If a professional craftsman has created the piece then there will be an excellent finish from every angle, not just the parts on show.

Going for a valuation

If you think your piece of jewellery may just be worth something then take it for a valuation. Often jewellers will charge for doing this for you, but some are more expensive than others. Sometimes auction houses do valuations for free.