An engraved agate gem dating from 35-25BC depicting the Roman Emperor, Octavian, as the god Mercury has been bought by the British Museum thanks to an Art Fund grant. The art charity, the National Art Collections Fund, donated £96,000 enabling the museum to reunite the gem with its pair, Octavian's sister Octavia depicted as the goddess Diana, already in the museum's collection. Director of the Art Fund, David Barrie, is delighted to have contributed to the £240,941 gem: Opportunities to acquire pieces of this quality and importance do not come along often. In securing this exquisite jewel, the Art Fund and the British Museum are reuniting these portraits after hundreds of years apart. The gems will now be exhibited as part of the Cleopatra of Egypt exhibition, launched this month.