The Church of Scotland is offering a reward for the return of the Moderator's official ring and cross, which were lost at Edinburgh Airport.
The jewellery was in a brown saddle bag on a luggage trolley outside the airport last Friday when it went missing.
The gold ring has an amethyst stone bearing a burning bush and St Andrews cross with the motto 'Nec Tamen Consumebatur', meaning yet it was not consumed - an allusion to the biblical story of the burning bush. The cross pendant is on a silver link neck chain.
The cross and ring are worn by the Church Moderator on official duties.
Reverend Albert Bogle, Moderator of the General Assembly, said: "I urge those responsible for taking these items, and accept this may have been done in all innocence, to look at themselves in the mirror, and see in their reflection that the right thing to do would be to return them as soon as possible - even anonymously.
"Please understand these are not my own items, the jewellery and cross are of significant historical importance and belong to the Church of Scotland and, through that, the nation itself. We are praying that these articles will be returned in the very near future."
The ring was stolen from the home of the previous Moderator at Christmas 2010 but the amethyst stone was anonymously returned and the ring was remade.
"When the cross and jewellery are returned, rest assured I and my future Moderators will continue to proudly wear and display them," Reverend Bogle added.
The Church is offering a four-figure sum of money for information that leads to the safe return of the items. Police urged jewellers to be vigilant and look out for the distinctive items.
A force spokesman said: "These items are of great historical significance to the Church of Scotland. Further to that, they're so unique and distinctive we would ask jewellers to stay vigilant should anyone try to sell them on. Anyone with any information should contact Police Scotland on 101, or the charity Crimestoppers anonymously on 0800 555 111."