This is a sterling silver choker with dolphin decorated with blue Gilson opal.

Gilson Opal is the 1st synthetic opal which has been successfully produced. In 1972, Pierre Gilson succeeded in synthesizing opals, and two years after in 1974 Gilson started to sell this man-made opal to the public as Gilson Synthetic Opal. Gilson Synthetic Opal is chemically identical to natural opal.