On July 9, 1871, two ragged, down-and-out prospectors walked into the Bank of California in San Francisco and approached a dignified-looking clerk waiting behind a giant oak desk. The two hungry-looking men quietly inquired about renting a safe deposit box. The clerk eyed the unkempt miners suspiciously before answering. “Why would you need such a box?” he asked impolitely. The men exchanged a knowing look and, after glancing around the room to see if anyone was nearby, dropped a buckskin bag in front of the clerk. Just as the clerk was reaching for the bag, it tipped over and several sparkling diamonds toppled out. The clerk’s eyes opened wide. “Diamonds,” he gasped. “Where did you get them?”

“Oh, up in the mountains,” one of the men said casually. “We sort of figured we better have a safe place to keep them while we go up and get more.”

The clerk gladly rented them a safe deposit box. The two put the sack inside it and sauntered toward the bank exit, staring around them at the splendor of the marble interiors.

Across town Mary Hamlin, a young woman with a slim figure, a round, gamine face, and golden blond hair, peered expectantly out of her upstairs hotel room window. When the two miners appeared on the dusty thoroughfare below, she opened the glass, casually took a seat on the sill, and glanced down at the men. She caught the prospectors’ eyes, and they nodded pleasantly to her as they passed. Mary batted her blue eyes at them while twirling a long curl of her hair around her finger. A devilish grin spread over her face and she laughed to herself as if she knew something the rest of the world didn’t.

A sudden gust of wind brought her to her feet, and she quickly jumped up and closed the window. She was still chuckling aloud as she checked her look in the mirror and exited the room. The emerald-green taffeta crinoline under her elegant dress rustled as she descended the stairs and made her way toward a poker table near a bar. The cowhands around the table shifted their attention from their cards to Mary. “You have any room for me, fellows?” she purred. The men quickly made a space for Mary, and she smiled indulgently at them as she took a seat. “It would appear I have more friends than fiddlers in hell,” she chortled.

The twenty-five-year-old lady gambler, better known to her competitors as Mary the Owl, purchased a stack of chips from the dealer and waited for the game to begin. Any hope her so-called friends had of winning a hand were dashed in no time. She had acquired her moniker because of her keen eyesight at the table. Few could beat her at five-card draw poker.

Mary was born in upstate New York in 1846. She was one of ten children and her family was quite poor. She left home at the age of sixteen because there wasn’t enough to eat. For four years she worked at a convent in New York City, training to be a nurse, but she abandoned the profession when she realized she could never earn enough money to fully support herself. When she was twenty she moved to Chicago and became involved with a con man named Philip Cartwright.

Cartwright was a sophisticated charlatan who took Mary into his confidence and taught her the trade. He saw in Mary all a person had to have to be a successful con artist: nerves of steel, a powerful imagination, and the calculating mind of a gambler. Cartwright helped develop her natural talent for swindling, but she eventually outgrew his direction.

Mary was never satisfied working small-time bunko games; she aspired to be a part of a large scam that would make her financially independent. After three years with Cartwright, she set out on her own. The gambling table provided her with a plenty to live on, and the occasional big score gave her a little extra. In late 1869 Mary pulled off an elaborate con with two other accomplices: Jimmy “the Peep” Coates and John Burtin, known as “the Smiling One” because he was always grinning. The three managed to sell fraudulent exclusive shipping rights to the Mississippi to a group of French investors. The job netted Mary more than a quarter of a million dollars.

Mary and her cohorts were not only exceptional swindlers, but excellent actors as well. Using makeup, costumes, and different accents, the three were able to assume various roles while keeping their true identities a secret. Hoping to take advantage of the wealthy gold mine owners in California, the group took their show west in 1871. While en route to the Gold Country, Mary conceived of a plan to separate the well-known banker William Chapman Ralston from his millions. The scheme turned out to be the West’s greatest hoax. Upon arriving in San Francisco in mid-June 1871, Mary and her coconspirators went to work setting the stage for the con.

Ralston was renowned throughout the frontier and often referred to as “the Magician of San Francisco.” He was dedicated to transforming the growing city into one of the world’s corporate and cultural capitals. To that end he built factories and gigantic hotels and invested in steamships, telegraph companies, and silver miners in Nevada’s Comstock. He was an ambitious, hopeful millionaire who saw unlimited possibilities in the development of the West.

Ralston created the Bank of California in 1863 and sold shares to twenty-two of the state’s leading businessmen. He managed to generate $2 million in capital funds and eagerly set out to financially back projects he believed would substantially increase his investments.

Mary had read about Ralston in the newspapers and felt there was a way to take advantage of his enthusiastic (and what some of his critics called “bold”) investment moves. She learned that the astute banker’s main weakness was his fanatical belief in California’s unlimited mineral wealth. San Francisco was in the midst of a second gold boom. The mines of 1849 had played out. There had been a slump in business, but new mines in Nevada brought the precious ore to San Francisco for shipment. The future looked bright, and people were talking about other minerals yet to be found.

There had been rumors of diamond fields in the hills of Northern California. Given the fact that so many riches had been found in the area, most believed in the possibility that there was an abundance of gems in the same location. Ralston was one of those believers. Mary the Owl knew this, and it became a major part of her plan.

Twenty minutes after Mary’s accomplices had entered the bank dressed as prospectors, news of their diamond mine had reached Ralston. He leaped to his feet and demanded that the clerk who spoke with the miners find them and bring them to him at once. Still dressed in their costumes, Jimmy and John were waiting in their hotel room when the clerk arrived. “Mr. Ralston wants to see you both,” he blurted out. “He’s real excited about the diamonds.”

“We ain’t wanting to sell any of our diamonds,” John answered. “Being as we have enough to eat on, we want to keep them until we bring in a real fortune.”

“Mr. Ralston doesn’t want to buy your diamonds,” the clerk assured them. “He just wants to meet you and talk to you.”

The two accompanied the clerk to the bank. Ralston was all smiles and cordiality. The con men were cautious and pretended to be dumb. They admitted they had found the diamonds in the mountains, but did not say where because they wanted to make a big haul first. Ralston was amused at their seeming naiveté. The banker was not out to steal anything from anybody. He envisioned a great diamond mine that would make California the center of the diamond trade and run the English and their African mines out of the market.

“Now, gentlemen,” Ralston said to the two, “you have discovered something big for you. You must realize that to develop this field will take millions. I am ready to advance you, say, $50,000 for an option to buy 70 percent of your interest. Your 25 percent will make you each fabulously rich.”

The two prospectors didn’t act like they were impressed. “Maybe we ain’t smart,” John said, “but we figure as how we can go out there and pick up a couple of million dollars in diamonds . . . that’ll be enough. Then we don’t care who knows about our field.”

That was the one thing Ralston feared. The last thing he wanted was this amazing find to be turned loose on the market. He knew the Old West, and he knew the bloodspilling this would cause. He knew also that in the end there would be no great diamond development for the Californians. But as he pushed his offer to buy an option, he ran into a peculiar refusal. Neither would say yes or no. Finally John said, “I’ll allow it if my sister can speak with you. She’s a schoolteacher and mighty smart. She can understand about this money thing.”

At that moment Mary stepped into the convincing scene being performed in Ralston’s office. She was adorned in a black dress, her hair had been grayed around the edges, and she was wearing glasses and makeup. She looked like a middle-aged schoolteacher. By the end of her conversation with Ralston, he had raised his offer to $100,000 and she had accepted.

Ralston entered into the agreement with the predictable stipulations. Before the money could be paid, he told them, he would have to have assurance there was a diamond mine where the two men claimed.

“Naturally, Mr. Ralston,” Mary said sweetly. “I would not permit my brother to take a penny from you unless he can prove to you there is a diamond mine.” Ralston was impressed with the honesty and forthright manner of the sister. He and two friends were taken to the spot where the prospectors claimed they had found the diamonds. A part of the way they were blindfolded. Mary had insisted on it, as she said, “to protect the interests of my brother and his friend.”

When the blindfold was taken off, Ralston and his friends were on the side of a foothill of the mountains. What they found dispelled any doubts Ralston might have had. They didn’t have to dig long until they brought up diamonds by the handful.

This settled the matter for Ralston. When he got back to San Francisco, he sent a cable to his friend and former partner, Asbury Harpending, in London. Harpending was preoccupied with his own business ventures and initially glossed over the matter. Once out of her costume, Mary let the word get out about the diamond find, and the news reached one of Harpending’s British associates. He warned Harpending not to take the report lightly, as America was a new and rich country and anything was possible there.

Ralston continued sending cables to Harpending in hopes that he would set aside all other ventures and concentrate on the diamonds. Harpending eventually did and then made way for California. After Harpending arrived he spoke with the two prospectors, checked their statements, and believed their story to be genuine. He made one requirement: The diamonds were to be examined by an expert at Tiffany’s in New York. This prompted Mary to join in the discussion. Harpending was as impressed as Ralston with her honesty and levelheaded way of protecting her brother. She agreed that the diamonds should be examined by an expert.

Harpending took the gems to New York, where he had Mr. Tiffany and his experts examine the stones. They pronounced the diamonds of rare value, worth easily $150,000. By this time the news of the diamond field had reached New York City. It caused a market stampede for shares of the new mining company, even though no company had yet been organized.

Harpending was not satisfied with the opinion of the experts at Tiffany’s, however. He insisted that a diamond expert from New York make a survey of the alleged diamond field. Mary again appeared for her brother. She was sweet but firm in her contention that the time had come for Ralston and the big boys to talk real money. After all, she argued, her dear brother was turning over to them a fortune of untold proportions and nothing had been said about what he and his friend were to get.

The gifted con woman played her hand shrewdly. She approved of the diamond field being seen by an expert, but before her brother agreed to any act that would disclose his secrets, an arrangement had to be reached first on how much money he was to get.

The Tiffany report had sent the hopes of Ralston and Harpending to soaring heights. They were easy suckers for Mary’s wiles. When she left the bank, she had secured $200,000 cash with $800,000 put in escrow, to be paid when the expert agreed that her brother had found the world’s largest diamond mine. Ralston and Harpending felt that they were taking no chances. They had $150,000 in diamonds as security for the $200,000, and if the diamond expert declared the find to be what they expected, the additional $800,000 would be a minor amount in comparison.

Ralston, Harpending, the gem expert, Jimmy, and John went to the diamond field. This time there were no blindfolds. The gem expert started his examination immediately upon arrival at the field. Everywhere he turned he found diamonds, and this time there were sapphires and opals at the location as well. The expert declared the field to be one of the greatest in the world and estimated it to be worth countless millions.

The expert and the investors were so excited about the discovery that they did not stop to consider two very important points: One, opals and sapphires are not a part of a diamond bed; and two, there were lapidary tool marks on many of the diamonds. Not only were those facts overlooked, but the expert, who was supposed to know diamonds, said they were of the finest quality.

The expert’s report clinched the deal for Ralston and Harpending, and they filed claims for the area. The $800,000 held in escrow at the bank was released to Mary and her accomplices. The three then quickly left the state.

The positive report by the diamond expert rocked the financial world, and news of the find was a newspaper sensation. Ralston and Harpending organized a company and were instantly flooded with requests to buy stock. The popular businessmen allowed only a handful to invest a total of $2 million each. Any plans they had for the funds that were to be made off the diamond field were short lived. One week after Ralston and Harpending established their company and gathered the capital needed to start mining, the truth about the diamond field was discovered. A young engineer and friend of Ralston’s was passing the diamond claim and stopped to investigate. He inspected a few of the gems scattered about and noticed they had been wedged in the crevices. Additionally, all had the marks of a lapidary tool—marks that raw diamonds do not possess.

When the engineer returned to San Francisco, he showed the cut diamonds to Ralston and Harpending. The two men were stunned at the discovery. Although they were embarrassed that they had fallen for the scam, they went public with information about the fraud and returned all the investors’ money. Four years after the incident, due to lack of funds, Ralston was forced to close the doors of the bank he had founded. Harpending left the business world as well and turned his attention to writing. In 1877 he penned a book on the outrageous con entitled The Great Diamond Hoax. In the book he defended his reputation against those who suspected he aided the con artists in their work. Authorities speculated that he bribed the diamond expert who authenticated the claim.

The executioners of the million-dollar swindle had gone their separate ways. John Burtin lost all his money gambling and was arrested in Cleveland for defrauding a widow out of her life savings. Jimmy Coates used his winnings to purchase a farm in Georgia. Mary Hamlin traveled to London and made her home in the country for ten years. In 1882 she returned to New York City, where she lived out the remainder of her days in luxury. She died in 1899 of natural causes.

Chris Enss is the COWGIRL Book Editor, and a New York Times Bestselling author who writes about women of the Old West. For more stories about these wild women, visit www.chrisenss.com for more information on her books.