He was surprised to receive a call last fall from someone claiming he had “one the largest opals” in the world.

Cline, a partner in Alaska Premier Auctions & Appraisals, stated that she was both extremely skeptical and excited about the prospect.

According to the auction house the opal is called the “Americus Australis” and weighs over 11,800 carats. It is also one of the most valuable gem-quality opals. It has a long history.

It was last seen in a linen closet in Big Lake, north Anchorage by Fred von Brandt who mines in Alaska for gold and whose family is deeply involved in the gem- and rock business.

The opal is bigger than a brick, and it is cut into two pieces. Von Brandt stated that this was a technique used to demonstrate gem quality decades ago.

Von Brandt stated that the stone was in his family from the 1950s when it was purchased by John Altmann, an Australian opal dealer.

Von Brandt stated that the opal had been in the custody of Guy von Brandt for many decades. He decided it was time to release it into the world and see what kind of interest it generates.

Von Brandt stated to The Associated Press that he had given me the task of determining which direction to take to get rid of the stone.

He said that the family, which has California roots, displayed the stone at various gem shows over the years until the 1980s. His father expanded his business into furniture, and he displayed the stone at his shop. Guy von Brandt eventually moved from Oregon to keep the stone, von Brandt stated.

Von Brandt stated that he took it to Alaska more than a year ago because he was trying to decide the best way to sell the item. He stated that he chose Alaska Premier Auctions & Appraisals as it was more likely to be noticed than a larger company. The sale will take place on Sunday.

Cline stated that the family has documentation regarding the origin of the opal. He also reached out to Fiona Altmann (granddaughter of John Altmann) as part of his research. She is the general manager at Altmann + Cherny, Sydney, Australia.

Altmann stated that her grandfather made frequent trips to Europe and the U.S. for business purposes.

Altmann stated that Cline emailed her and she was skeptical. The name of the stone in particular threw Altmann. She said that she began digging and found “something with my grandfather’s handwriting, the picture of an opal, and the word ‘Americus Australis.’”

She said, “I can 100% confirm that their provenance information matches what I have.”

According to the auction house, the stone was found in the same Australian field as the “Olympic Australis” opal. It weighs 17,000 carats. According to Altmann’s company, the Olympic was among the stones John Altmann and Rudi Cherny purchased in 1956.

Auction company Cline is looking for minimum bids of $125,000 to participate in Sunday’s auction. Cline stated that it is a calculated risk. The company will take a conservative approach to get the best attention and continue to pursue its goal of attracting the most attention. Cline stated that the company has set a target price of $250,000-350,000.

A smaller piece of the opal, which von Brandt claimed his father had cut off, is included in the sale. It can be worn or displayed.

Gemological Institute of America spokesperson said that they couldn’t comment on the opal because they haven’t seen it. The Associated Press reached out to other people who didn’t respond or weren’t familiar with the stone.

Altmann and von Brandt both said that they would love to see the piece of opal end-up in a museum. Von Brandt stated that he believes the auction will be both exciting and challenging, more so for my father than me.

His father was a young child when the stone was acquired by the family. He said that he feels a deeper connection to the stone than anyone else.

Von Brandt stated that they both feel “nervous excitement”. “I believe it’s going well, and we are optimistic.”