A three-carat gem was shipped at least four times between shadowy companies allegedly controlled by Indian billionaire Nirav Modi. The practice of round-tripping – trading goods repeatedly to give the appearance of distinct transactions – was central to the largest bank fraud in India.

https://www.smh.com.au/world/asia/globetrotting-three-carat-diamond-at-the-centre-of-largest-bank-fraud-in-indian-history-20180830-p500sz.html