Story By: Kathryn Quinn, Sub-Editor:  Joseph Golder, Agency: Central European News  This chocolate costs an eye-watering 6,268.50 GBP per kilogramme and Guinness World Records have listed it as the planet's priciest. The chocolate, produced by the company Attimo Chocolate in Zurich, the capital of the canton of Zurich in north-central Switzerland, which launches this month,…