Inside the state park where visitors dig for diamonds

It was a scorchingly hot day in Murfreesboro, Arkansas, but Kenneth Gillespie wasn't ready to give up on his dream of hitting it big just yet.

Since quitting his teaching job, Gillespie has been spending a lot of time at Crater of Diamonds State Park, hoping to strike it rich.

“This is my vacation from life,” he told ABC News. “And there’s a potential to hit something. I see the mine like buying a scratcher.”

Gillespie is far from alone. For a $10 admission fee, anyone can come and try their hand at diamond digging, and according to the park’s website, more than 182,000 people visited last year alone, unearthing a total of 445 diamonds.

Hundreds of millions of years ago, a volcanic eruption more than 100 miles below the earth's surface left precious jewels scattered throughout the soil of the 911-acre park, according to Jeff Post, curator of the National Gem and Mineral Collection at the Smithsonian Institution.

“The diamonds were entombed in the cooled volcanic rock, lamproite,” Post told ABC News. “Subsequently, the rock eroded to form the lamproite soil and the scattered diamonds.”

Al and Alberta Fling are regular diggers who moved from Colorado and now live nearby the park. The couple is among the more serious treasure hunters who rent seasonal cages to up their chances of finding diamonds.

“It originally started when my wife lost her wedding band,” Mr. Fling told ABC News. “I promised her something, and don’t promise something that you can’t hold up to.”

Al Fling found a 0.77-point canary yellow diamond, but the couple kept coming back.

“Now what I’m doing is playing,” he laughed. “I’m enjoying it. I don’t have the pressure of finding the wife that diamond now.”

But Alberta Fling said her dream is to take home a 10-carat stone.

“That would make me plenty happy!” she told ABC News.

The Flings aren't the only couple out in the fields finding diamonds in the rough.

In 2011, Kenny and Melissa Oliver found a 2.44-carat diamond they called the "silver moon." It was later appraised for more than $21,000.

“When I took the screen out of the water, that big rock was sitting there and I knew what it was!” Melissa Oliver told ABC News.

She said their families still don't understand their passion for digging.

“Our families and friends, you know, think we’re crazy!” she said. “They say, 'Y'all are crazy, it’s too hard of work to find a diamond.’”

But, she explained, "it’s not actually finding the treasure. It’s the quest.”

Not everyone's quest ends with bling, however.

“Diamonds are not easily found,” Bill Henderson, the park's assistant superintendent, told ABC News. “Not only does it take a lot of expertise and determination, sometimes you have to be a little lucky, too, to find it.”

Near where Gillespie was hunting for diamonds, Rick Clause sifted through mounds of soil.

“Today is our 31st wedding anniversary, so I thought we’d come and try and find a diamond,” Clause told ABC News.

He and his wife, Charlotte, had traveled from Louisville, Kentucky.

“Remember when Charlie Brown went trick or treating? All he ever got was rocks,” Clause laughed. “That’s all I ever got.”

To find the diamonds, diggers bring loads of soil to water troughs to sift through, searching for a sparkle. Most of the diggers use communal water troughs for sifting, and they're where many tourists are directed to when they first come to the park.

As Rick Clause dipped the rocks he had found in the water, his wife rested in the shade.

“It’s just hot,” Charlotte Clause said, sounding somewhat exasperated. “It’s time to go.”

But for those who are willing to come back day after day, die-hard diggers say there's more than stones to be gained.

As Alberta Fling sifted through piles of dirt using an improvised strainer and a rusty wheelbarrow, she said she enjoys coming to the park because it gives her "a solitude."

“When you go home, you rest well,” she said. “And your life’s more enriched for it.”