The world’s most valuable private jewellery collection will go on display in London from Saturday before what is expected to be a record-breaking £120m charity auction. The more than 700 items of jewellery collected by the late Austrian billionaire art collector Heidi Horten is on a world tour, taking in New York, Singapore, Taipei and London, in the run-up to a four-part auction at Christie’s in Geneva next month and online. Some of the top pieces will be on public display at its St James’ auction room in central London from Saturday until Wednesday. The collection includes a white gold...