Only a few historians remembered that the Koh-i-Noor, which weighed 190.3 metric carats when it arrived in Britain, had had at least two comparable sisters, the Darya-i-Noor, or Sea of Light, now in Tehran (today estimated at 175–195 metric carats), and the Great Mughal Diamond, believed by most modern gemmologists to be the Orlov diamond (189.9 metric carats), today part of Catherine the Great’s imperial Russian sceptre in the Kremlin.8 In
