Campbell Bridges was something of a real life Indiana Jones. An Ernest Hemingway lookalike in tropical jacket and hat, a lone mzungu, or white man, in the heart of Africa, he spent his nights in 30ft-high treehouses to avoid elephants, lions, rhinos, venomous cobras or scorpions in his quest for precious gems of sparkling blue or green. He was one of the first to mine the blue-purple gem tanzanite and it was he who, in 1967, uncovered a previously unknown garnet, the deep-green tsavorite, brighter than emerald, that now gleams against the black velvet of Tiffany’s windows in Manhattan and London.