I wanted to know what the letters PI{HGE} stand for when describiinh a gold coin?

HGE means Heavy Gold Electroplated

Often "Gold Pl" means Gold Plated, could be misinterpreted or misspelled as PI.

Generally a copper or alloy coin that has been plated with gold.

P.I. Is a mint of coinage in the Philippines. See Manila Mint (http://en.wikipedia.org/wiki/Manila_Mint)