Rare $675,000 opal makes public debut

The world’s finest uncut opal, a 998-gram gem called the Fire of Australia, has gone on permanent public display for the first time since its discovery more than 60 years ago.

Valued at more than $675,000, the stone is the largest known high-grade opal in the world, according to the gem’s new owners, the South Australian Museum in Adelaide, Australia.

“The Fire of Australia is around the size of a softball…and shows all the colors of the spectrum,” museum director Brian Oldman told CNN, emphasizing the extreme rarity of the stone.

“The opal is unique because of its high quality and large size. It throws off a lot of red, which is one of the indications of a highly valuable piece of opal.”

Desert find

The gem was first discovered in 1946 by miner Walter Bartram at the Eight Mile opal field in Coober Pedy – a small desert town in South Australia famous for its opals.

(South Australia, which encompasses a vast arid area in the south and middle of Australia, produces more than 90% of the world’s precious opal, according to Oldman.)

View this interactive content on CNN.com

Oldman said it would have been part of a larger seam of opal that ran underground, and would have been extracted in pieces.

Recognizing the uniqueness of the piece, the Bartram family, who own an opal mining and distribution business, held onto the piece.

Read: Historic banknote found inside ancient Chinese sculpture

“The Bartrams polished two sides of the Fire of Australia, as they recognized that it was a significant discovery and wanted to show the quality of the opal,” Oldman said.

“Usually a large piece of opal doesn’t get polished at all. Instead, it gets cut up for jewelry and then it gets polished.”

The stone remained in the family for more than 60 years, spending most of that time in a safety deposit box. But after loaning it out to the South Australian Museum for an exhibition, Walter Bartram’s son, Alan, said the family decided to place the heirloom “in safe hands.”

“We’ve been long term supporters of the South Australian Museum and it seems fitting that it should be passed onto the people of South Australia to enjoy,” he said in a statement.

Heritage Auctions

The earliest known stone copy of the Ten Commandments sold at auction in Beverly Hills in 2016 for $850,000.

Heritage Auctions

The stone was first uncovered in 1913.

Heritage Auctions

"The tablet's significance is testament to the deep roots and enduring power of the Commandments that still form the basis of three of the world's great religions: Judaism, Christianity and Islam," says David Michaels, director of ancient coins for Heritage Auctions, who will be conducting the sale.

courtesy mossgreen auctions

Specialists at Mossgreen auctions in Australia discovered this Ming dynasty banknote hidden inside the head of this 14th century Buddhist carving. The wooden sculpture represents the head of a Luohan -- an enlightened person who has reached Nirvana in Buddhist culture.

courtesy mossgreen auctions

Its face value was worth roughly $98 at the time of its circulation and the 700-year-old banknote is believed to have been handmade during China's Ming dynasty. Together, the banknote and sculpture are expected to fetch between $30,000 to $45,000 at auction.

courtesy mossgreen auctions

After studying the banknote and carving details, art specialists were able to estimate the sculpture's age, which dates back to China's Hongwu period in the 14th century.

courtesy mossgreen auctions

Mossgreen specialists believe this is the first time a Ming dynasty banknote has been found inside a wooden Buddhist sculpture. They say it's more common to find relics and semi-precious stones left by monks inside Buddhist sculptures.

Uruma Board of Education

Ten ancient Roman and Ottoman coins were recently discovered in castle ruins in Okinawa, Japan. This image shows the front of one of the Roman coins.

Uruma City Educational Board

"I couldn't believe they'd found coins from the Roman empire in Kasturen castle," archiologist Hiroyuki Miyagi, from Okinawa International University, told CNN. This is the front of one of the Ottoman coins.

UNC Charlotte

Archaeologists recently unearthed a rare 2,000 year old Roman coin during a scientific dig in Jerusalem. The gold coin features the face of Emperor Nero and was likely struck in 56-57 AD.

Aileen Cynthia Amurao

In August 2016, the world's largest pearl was discovered under a bed in the Philippines, where it had lain forgotten for over ten years.

Courtesy de Grisogono

This 1,109 carat, tennis ball-sized diamond made headlines in November 2015 when it was pulled out of the Karowe Mine, in Botswana, by Canadian company Lucara Diamond Corp.

Clara Amit, Courtesy of the Israel Antiquities Authority

In May 2016, divers discovered a 1,600-year-old shipwreck while swimming the ancient Roman port of Caesarea. These rare bronze artifacts were recovered from the ship.

ATLAS

Over 1,300 pounds (590 kg) of bronze Roman coins dating to the 3rd century A.D. were unearthed in April 2016 by construction workers digging a trench in Spain.

Béla Polyvàs, Canton of Aargau

In January 2016, over 4,000 Roman coins were discovered by a fruit and vegetable farmer on a molehill in his cherry orchard in Switzerland.

courtesy william henry

The bead on this bracelet, from Portland-based design company William Henry, is actually made using fossilized mammoth tooth and dinosaur bones.

The South Australian Museum purchased the opal with an Australian government grant. The Fire of Australia will be on show in the museum’s foyer until February 28, before taking its place alongside the museum’s extensive permanent collection of Australian precious opal.

Polished history

Although impressive in its own right, the Fire of Australia is not the most valuable opal in existence.

The largest and most valuable single piece of rough gem opal is the Olympic Australis, a 3.45-kilogram, 17,000-carat stone estimated to be worth about $1.9 million.

Read: Swiss jewelers acquire world’s most expensive rough diamond

The stone was purchased by Altmann + Cherny jewelers in 1956, and has been on display in their showroom in Sydney, Australia, ever since, according to Fiona Altmann.

In terms of polished stone, the Virgin Rainbow, a rare crystal opal that’s also owned by the South Australian Museum, is the world’s most expensive opal on a per gram basis, valued at $750,000.