Of all the things that could go wrong on a wedding day, losing a diamond ring that's also a 100-year-old family heirloom is up there with a bridal hair bee infestation and being forced to wear big, grey knickers under your gown.

It happened to one bride an hour before she was due to walk down the aisle - but thanks to an eagle-eyed eight-year-old, her wedding woe turned into a heartening tale of honour and thankfulness.

Wisconsin bride Erica Fenske was posing for photographs in front of the picturesque Lake Michigan shoreline minutes ahead of her wedding on Saturday when she realised her grandmother's solitaire diamond had popped off her finger.

"It's a small solitaire ring,” Fenske tells WISN. “My mother wore it in her wedding. I think my grandmother wore it in her wedding as well.”

Bride loses ring an hour before the wedding...little boy saves the story