Australia, Victoria (1837-1901), 1/2 Sovereign 1887 (Sydney mint) (Gold, 3.99 gr, 19 mm) KM 5. PCGS AU58
Quite scarce to find in such grade, with only one finer at PCGS, and none at NGC, this is probably the best grade currently available on the market.
See similar coin (NGC AU58) at Heritage Auctions, Inc., Auction 3024 (2013), Lot 23033. Sold $3.290