(IDEX Online) - The flaws that reduce the value of a diamond are helping scientists how our planet was formed.They've developed new techniques that allow them to tell the age of a diamond from tiny "microinclusions" of fluid trapped during its formation.A team at The Earth Institute, Columbia University, USA, has examined diamonds from Africa and identified three distinct periods in which they were formed, according to research published in the open access journal Nature Communications.First was during the Proterozoic age, 2.6bn to 750m years ago, when rocks collided into great mountain ranges. Then came the Paleozoic age (540m to 300m years ago) by which time the African mantle-to-be were forming.And finally, the Cretaceous period (130m to 85m years ago) in which diamonds were formed from what once was the ocean floor."Southern Africa is one of the best-studied places in the world, but we've very rarely been able to see beyond the indirect indications of what happened there in the past," said Columbia University geochemist Cornelia Class.Researchers examined diamonds provided by De Beers and found that diamond-forming fluids changed through these three ages, from carbonate to silicone and then to saline.Pic courtesy Yaakov Weiss, Columbia University