Oxygen isotopes and emerald trade routes since antiquity

Oxygen isotopic compositions of historical emerald artifacts from the Gallo -Roman period to the 18th century indicate that during historical times, ar tisans worked emeralds originating from deposits supposedly discovered in t he 20th century. In antiquity, Pakistani and Egyptian emeralds were traded by way of the Silk Route. Together with Austrian stones, they were the only source of gem-quality emeralds. Immediately after the discovery of the Col ombian mines by Spaniards in the 16th century, a new trade route was establ ished, first via Spain to Europe and India and then directly via the Philip pines to India. Since then, Colombian emeralds have dominated the emerald t rade, and most of the high-quality emeralds cut in the 18th century in Indi a originated from Colombia.