Duryea Gem Manufacturing Co. was based in Philadelphia, Pennsylvania, and represented the final automotive venture of Charles Duryea. The company produced a three-wheeled cyclecar known as the Gem, which used the same engine and drive system as Duryea's four-wheeled model of 1914–15. The chassis for the Gem was built by the Detroit Chassis Co. The Gem was promoted with considerable enthusiasm, being advertised as "the biggest idea in the history…