The CIBJO Coloured Gemstone Commission presented newly released Opal Guide incorporating the wide range of possible opal types, during its session on September 6, 2026, at the CIBJO Congress in Vicenza, Italy..

Developing agreed definitions was an important step in the updating process, Coloured Stone Commission President Charles Abouchar said.

The guide lists opal origins including Australia and Ethiopia, as well as lesser-known deposits, such as those in Bulgaria, Abouchar said.

He discussed the definitions set out in the CIBJO Gemstone Blue Book, noting that there had been consistent agreement to use the term “synthetic” for gemstones that are not natural.

Damien Cody, president of the International Colored Gemstone Association, thanked those who contributed to the update of the Opal Guide.