The seas were high and the fog was thick in December 1746 when the Prince de Conty, a French frigate returning home from China with tea, ceramics and roughly 100 gold ingots, foundered in the Atlantic, just 10 miles from shore. Its bounty sank beneath the waves and laid untouched for 228 years until 1974, when treasure hunters located the wreck and illegally scavenged its remains. On Wednesday, five of the gold ingots, embossed with Chinese characters and valued at $231,000, were returned to the French Embassy in Washington, ending…