Polished Baltic Amber with Insects Oligocene Period, circa 45 million B.P. A regular block of polished Baltic amber with several Diptera insects. 16.3 grams, 51 mm (2 in.). From the Baltic Sea Coast, Primorskoje mine, Kalliningrad. English collection formed in the 1990s. UK art market. Property of an Essex gentleman. accompanied by an illustrated identification card with provenance.