The stone, dating to the Hellenistic period, was found at the Tel Dor excavation site south of Haifa, the Israeli news Web site Arutz Sheva reported Wednesday.
The stone is less than a centimeter long (less than a half-inch) and less than a half-centimeter wide, Ayelet Gilboa, one of the archaeologists directing the work, told the news Web site. The type of gemstone wasn't described.
Gilboa said the carved image shows a young and energetic face, with a sharp chin, straight nose and long curly hair held in a crown, the Web site said.
The gemstone was found in the remains of a large public building dating to the period from the death of Alexander in 323 B.C. to the final conquest of Greece by the Romans in 146 B.C., and was authenticated by Jessica Nitschke of Georgetown University in Washington and Andrew Stewart of the University of California at Berkeley, the Web site said.
The conquering Greek king is believed to have passed through the area while making his way to Egypt.
Tel Dor , on the Mediterranean Sea, was an important international sea port in ancient times. Excavations began there in 1980.