The couple-opal cutters and retailers respectively-had no previous experience in finding opals, but under the guidance of local senior miner Rod Griffin and experienced friend David Darby, they went on an expedition. The expedition was filmed for the Discovery Channel's Inland Opal Hunter series.

This is the most valuable discovery recorded in the series so far, almost five times the $250,000 previously recorded. 

Sofia Andreou operates Opal Earth/Whitsunday Opals in Airlie Beach, Queensland. This is a second-generation opal jewelry and bulk opal shop. The siblings have inherited their love for opals from their parents who opened in the 1960s.

Describing this discovery, Sophia told the Daily Mail, “This is a mix of shock and sheer surprise.”

Isaac added: "Words can't describe the way the heart beats, my hair stands up."

Yowah is located more than 900 kilometers southwest of Brisbane and is known for its opal mining and opal mining areas. Yowah nuts-a rare boulder opal encased in iron ore-were found there. 

Andreous's 150-kilogram findings include Yowah nuts-a specimen called "Yowah Moon", valued at $50,000-and Koroit nuts, also known as Koroit matrix opals.

Yowah hosts the annual Opal Festival every year, and the 2021 event will be held from July 16th to 18th.

At the same time, the devastating March floods on the east coast of Australia had a positive impact on other potential gem hunters, with tourists flocking to the gem mines in central Queensland to look for sapphires, ABC reported.

Gemfields is located approximately 900 kilometers northwest of Brisbane and includes designated gold rush areas including Willows, Sapphire/Rubyvale, Glenalva and Middle Ridge. The flood washed away the top soil, making shallow pan washing easier.

The color of sapphires in this area usually ranges from cyan to green, yellow and blue. 

Read more: The record-breaking opal of the beauty of Australian sapphires sold for $850,000 at the Australian gem auction: Opal