A bride has been left "heartbroken" after her hand-made engagement ring was stolen - on her wedding day. A cold-hearted thief is believed to have swiped a black handbag containing the sapphire and diamond-encrusted platinum band from a secluded village church in Sussex as Caroline Marshall, 32, and James Granshaw, 29, said their vows.

Distraught family members said the bride was left in floods of tears when she realised her beloved ring was missing following the service in Saturday afternoon.

They are desperately trying to track down the £6,000 ring, which they say has "priceless" sentimental value as it was lovingly hand-designed by her husband at an ethical London jewellers.

James' father Mervyn, a retired airline pilot from Guildford, said: "It is just appalling to do this to a bride on her wedding day.

"This was not a drive-by or a walk-by theft, someone has walked up to the church and targeted it. I just despair. To steal a bride's engagement ring from a church - how low can you go?

"It put a cloud over the whole day. They are totally heartbroken at what has happened. We are trying to reassure them, but Caroline has been in floods of tears on her honeymoon because she is so upset."

James, a qualified barrister and legal adviser at Waverley Borough Council, spent months painstakingly researching ethical jewellers to design an engagement ring that did not contain so-called 'blood diamonds' - which are mined in conflict zones - and only used ethical materials.

And he helped to design the "irreplaceable" ring himself.

After getting engaged on the snowy ski slopes in Switzerland in 2012, the couple and their family and friends gathered at the parish church of St Peter ad Vincula in Wisborough Green, West Sussex last Saturday for the nuptials.

But moments before the ceremony was due to start, Caroline, who works in compliance for an investment firm in the City of London, realised she still had her engagement ring on. She slipped it off her finger and gave it to her best friend and bridesmaid, who put it in her black LK Bennett handbag for safekeeping.

After the service they realised the ring was missing and called the police.

The stolen handbag also had an iphone in it, and the frantic couple were able to track the device for a couple of hours and saw it was making off towards Haywards Heath before the signal went dead that evening.

Caroline and James have jetted off for a two week honeymoon in the borders of Tuscany, Italy, but their family say the theft "blighted" what should have been the happiest day of their lives.

Mervyn, 60, said: "The bridesmaid feels so guilty - it is her best friend. My son and Caroline have gone on their honeymoon, but it has cast a huge shadow over the day.

"The engagement ring is unique. It is not worth £10 million, but it has huge sentimental value.

"James put in a lot of effort to create that ring because he knew she would appreciate it. They go to great lengths to make sure it is ethical. It is not some off the shelf ring, it took months of organisation and she loved it. Now it is gone."

The couple fear the thief intends to sell their prize possession to one of the dozens of famous jewellery shops in the Lanes in Brighton, and they are urging anyone who has any information about the ring to get in touch.

A Facebook page called 'Help us find the ring' has been set up to help the search and has received almost 200 likes, and friends and family are using the twitter hashtag carolinesring.

A spokesman for Sussex police was not immediately available to comment but the force have re-tweeted the appeal.