Fiona Bruce introduces unscreened gems from recent shows.

Experts investigate some fascinating finds, including a garnet and diamond cross believed by the owner to have been gifted by Marie Antoinette en route to the guillotine. A suitcase of unopened letters from an imprisoned soldier in World War I finally reveal their secrets. There is also an attractive Arts and Crafts casket once intended to be the final resting place of a grandmother's ashes. And an emblem of survival amidst the chaos and destruction of Berlin at the end of World War II is touchingly depicted by a plaque of a butterfly made from crushed brick, tiles and broken glass taken from the ruins.