Necklace, 14k white gold, lucite pendant

Necklace, 14k white gold, rectangular lucite pendant, 23mm long x 11mm wide x 7.5mm thick, with 10 round diamonds forming number 1on a 20” sterling silver rope chain Necklace is circa 1980 There is a tiny ding on the bottom left front side of pendant which can be seen in photos My mother was the original owner