SANTA ANA, Calif. -- It's been called the greatest lost treasure in U.S. history. More than $50 million worth of gold sank to the bottom of the ocean when the SS Central America sank in a storm in 1857. What unfolded afterward is a tale of tragedy, deception and ultimately discovery. Now the treasure will go on display at the Long Beach Expo Thursday, Feb. 22, through Saturday, Feb. 24.

Before that could happen, slowly and carefully, more than a century of sediment was removed from the treasure: some 3,100 gold coins and more than 10,000 silver coins, all recovered in 2014 from what's known as the "Ship of Gold."

"This is a whole new season of discovery for me," said Bob Evans, chief scientist and curator of the treasure. "There's something new and wonderful comes out every day. They have stories to tell."

Gold bars recovered from the 1857 shipwreck of the USS Central America. CBS News

The story began in 1857 when the SS Central America went down in a hurricane about 160 miles off the coast of South Carolina. Four-hundred-twenty-five people died in the storm, reports CBS News correspondent Jamie Yuccas.

"This was a largely forgotten moment in American history because a few short years after that, the Civil War broke out," Evans said.

During the California Gold Rush, the 285-foot steamship shuttled tons of gold from the West to banks in the East. The gold deliveries were essential in helping maintain the nation's economic stability.

Evans began hunting for the sunken treasure more than 30 years ago. He was aboard the expedition lead by Capt. Tommy Thompson in the late 1980s when they first spotted what they called the "Garden of Gold" more than a mile below the surface.

"Gold bars and coins ... lightly covered with sediment. That's kind of what's fascinating about it in some ways. You've got this coral that is like growing right out of a block of gold," Evans said.

Using a robotic vehicle they'd built in a garage, they were able to scoop up some $50 million in gold. But investors who helped finance the $13 million expedition claimed Thompson never paid them. He disappeared along with hundreds of gold coins.

"The marshals hunted for him for two and a half years," Evans said. Authorities finally found Thompson in 2015. He remains behind bars for refusing to answer questions about the missing coins.

A second salvage effort was launched in 2014. After years of legal wrangling over ownership of the treasure, Dwight Manley, a former sports agent and coin enthusiast, purchased the rights to the fortune.

"There are dozens of coins this time that are the finest known," Manley said. His passion for coins began as a child collecting pennies. By age 12, he had his own business cards.

"They're like little time capsules every time you hold one, who had it before, what it was for," Manley said.

Manley is putting the coins up for sale. He believes one in OK condition could fetch a few thousand dollars. But you'll need deep pockets to buy a gold bar.

"Something like this would be $250,000," Manley said, holding a small bar of gold in his hand.

A gold bar recovered from the 1857 shipwreck of the USS Central America. CBS News

During the second expedition in 2014, a safe was found. Inside was a saddlebag packed with bundles of personal treasures. For the first time since 1857, Evans opened one, finding a stickpin and brooch made from gold nuggets.

"That's what little kids want to do, they want to fantasize that they find a secret room full of gold. Well, that's what these bags are," Manley said.

From a rare $20 gold piece to everyday pocket change – call it a token bonus, a small addition to the find of a lifetime.

"The 45 ingots are roughly $12 million," Manley said.

If you're wondering if there's any more treasure down there, Dwight tells us there are still two areas they weren't able to get to – so who knows!