Polished Baltic Amber with Various Insects and Spider Oligocene Period, circa 45 million years B.P. A polished specimen of amber with spider and various insect inclusions. 29.8 grams, 79 mm (3 1/8 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.