Ring with a Blue Gem (500 BC). Its writing means “Made by Dexamenos of Chios”. The gem itself is from Kerch, modern-day Crimea.
The master Dexamenos, of Chios, signs four gems, and others can be assigned to him for their style and command of detail, sometimes engraved by hand and not by the cutting wheel. He worked in the third quarter of 5th Century BC and seems to have had a fondness for mottled jaspers for his work.
The Hermitage - St. Petersburg