The stolen Unspunnen stone, an ancient symbol of the Bernese Oberland, was handed back on Saturday night after having been in the hands of Jura separatists for 17 years.
During an Expo reception in Saignelégier, two strangers presented the ancient stone to Shawne Fielding, the wife of the Swiss ambassador to Berlin who had just been nominated an ambassador for the national exhibition, Expo.02.
Fielding also received a bunch of flowers and a letter demanding the reunification of the canton Jura. The letter said: "We hereby present you with a few flowers and a big sweet from the Swiss Alps. We hope you will digest it better than we digested the separation of the Jura."
The Jura separatist group "Béliers" stole the 195-year-old stone, which weighs 83.5 kilogrsammes, from the tourist museum in Interlaken in June 1984.
The group is campaigning for the political reunification of canton Jura, which has been disputed since the 10th century.
After many years of conflict, canton Jura was founded in January 1979 but three districts remained with canton Bern. The Béliers group demanded those three districts should come under the authority of the canton Jura.
The Unspunnen stone is an important part of various stone throwing competitions in Switzerland, which was first used at the Unspunnen festival in 1805. Since the theft 17 years ago a copy of the ancient stone has been used for the competitions.
swissinfo with agencies