The fabulous gem was in the spotlight for a presentation by Dungog resident, psychologist turned opal miner and cutter Toby Solomon.

The May 17 event started with organisers having to put out more chairs, as people crowded into the Dungog CWA hall, and ended with a noisy buzz of conversation around Toby and her display of opals and potch.

"The audience, ranging in age from 9 to 90, was fascinated by Toby's description of life in the Grawin Opal Fields near Lightning Ridge," said Ruth Dirks from the Science Hub.

Toby described the composition and range of opals, dispelled myths, especially the one about opals bringing bad luck, and explained why the colours appear different from different angles.

Her talk was illustrated throughout, showing the changes in mining practices today from those in the early 1900s, the claustrophobic interiors of mineshafts and a stunning array of products of Toby's mining experience.

"Toby used a map of the location of the seven major opal fields in Australia to explain how characteristically different are the opals from the different fields," said Mrs Dirks.

"She showed photos of her opal-cutting equipment, which garnered many questions from the kids in the audience.

"Toby explored the difference between precious opal and common opal or potch: she explained how potch can be glued to very thin pieces of precious opal to make doublets. Opals are hard but some care needs to be taken - they are susceptible to scratching.

"The harsh reality is that in the marketing chain opal miners take the most risks and receive the least financial reward. Opals then pass through cutters, buyers and jewellery manufacturers to the retailers who have the lowest risk and highest profit. Miners work under harsh conditions too: not everyone in the audience agreed with Toby that mining looked like "fun"."

With plenty of audience participation throughout the evening, people left feeling they had been close to the opal mining experience Mrs Dircks said.