During his sparkling career, this world-famous diamond dealer has sold gems to Oprah Winfrey, Donald Trump and Dame Elizabeth Taylor. Graff’s life among the glitterati is quite the reversal of fortune. He grew up in East End poverty and left school at 14, scrubbing toilets in his first job at a jeweller in Hatton Garden, London. His chain of nearly 70 boutiques includes premises in Dubai, Monaco and Singapore. Sourcing the most perfect diamonds and ensuring the highest levels of customer service have kept the super-rich calling. Although the company’s finances are not exactly transparent, Bloomberg has valued the company at £7.7bn. We are more cautious.