The great Yuma diamond hunt

“Diamond field located in Western Arizona,” the newspapers reported in 1871.

The papers got wind of the story when two rough-looking miner types deposited the diamonds in the Bank of California's vaults in San Francisco for safekeeping. Phillip Arnold and John Slack, the owners of the stones, estimated their value at $125,000. The gems were rough and uncut, just as the finders said they found them on the ground. Included in the collection were several red stones that the pair thought were rubies.

William Ralston, president of the bank, was immediately interested. He introduced himself to the miners and indicated his interest in their diamond field. The pair seemed reluctant to talk about their discovery. They seemed to be ignorant prospectors who knew little about banks and financiers and distrusted both.

But Ralston persisted, explaining that mining operations were expensive propositions and that with the help of businessmen such as himself, all of them might become wealthy. Ralston explained that he and two fellow financiers, George Roberts and William Lent, were willing to buy an immediate interest in their claim.

The offer of immediate money seemed to loosen the miners' tongues. They poured out a story of finding the stones lying right on the surface in a remote section of the West. “We even found one atop an ant hill,” Slack exclaimed.

While Ralston wasn't eager to let the entire country in on the diamond discovery, it wasn't possible to keep the secret from employees in his bank. They soon leaked the news, and it became an immediate topic of discussion all over San Francisco.

When the papers picked up the tale, eager reporters cornered Arnold and Slack. After badgering the pair for some time, the miners conceded that their great discovery had been made in southwestern Arizona. “But we're not telling more than that,” they announced.

Yuma's newspaper, the Arizona Sentinel, picked up the story in August, 1872. By that time, the early excitement caused by placer strikes at Gila City, about 15 miles northeast of Yuma, and La Paz, near present-day Ehrenberg, was over. Both gold placers boomed for a time, but died as quickly. Gila City was dead by 1862 and La Paz by 1871. The news that there might be diamonds around Yuma caused a great deal of excitement.

“Many of our good citizens can be seen early in the morning and late in the afternoon, on the hills surrounding out town, searching for precious stones,” Yuma's Sentinel told its readers. No one wanted to be left out if fortunes were to be made, not even District Judge DeForest Porter. Judge Porter and Clarence Gray, a member of the legal fraternity, were among the first to think they had found precious stones.

“A man named Baker offered me $500 for the one I found,” the judge told a reporter.

“Did you sell it?” the reporter wanted to know.

“No, I kept it,” Porter answered. “It must be worth much more than that.”

Believing themselves on the verge of becoming rich, Judge Porter and a “mining expert,” Julius Siebeck, organized a diamond-hunting expedition which left Yuma several weeks later. After disappearing into the desert for several days, they returned empty-handed. “The diamond expedition which left here last week, having met with a misfortune, returned a few days ago,” the Sentinel announced.

The Sentinel never disclosed what kind of misfortune had overtaken the expedition, but one suspects it was a scarcity of diamonds. The judge should have taken the $500 for his “diamond” and left town.

In the meantime, William Ralston and his associates were demanding proof that the diamond field existed. Arnold and Slack assured them that it did and explained that the story about the location being in Arizona was a deliberate lie. “We spread that tale to prevent the possibility that someone might accidentally find our diamond mine,” they said. “It is really in Wyoming — not Arizona. If you want, we will be glad to take someone there who is an expert to examine it for you.”

Henry Jannin, a mining engineer with a good reputation, was selected to visit the diamond field. With Arnold guiding him, Jannin picked up a bag of assorted stones. Jannin pronounced the Wyoming diamond mine genuine even though he had no previous experience with precious stones.

While Ralston, Roberts and Lent were celebrating their good luck, Clarence King of the United States Geological Survey accidentally found the diamond field in the southwestern corner of Wyoming. “It's a fraud,” he announced after a careful examination. “The gems exist in positions where nature alone could never have placed them.”

Indeed they did. One was lying in the fork of a tree. Diamonds were there, but they were cheap stones which a confederate of Arnold and Slack had purchased in Europe. Jannin had been fooled by a salted diamond mine.

Arnold and Slack got about $660,000 from Ralston, his partners and other investors. The diamonds they turned over to the businessmen were proven to be of little value.

Estimates suggest they were worth $35,000. Lawsuits over the swindle jammed the courts for several years, but when it all ended, no one went to jail.

Ralston, a major victim, was ruined financially. On Aug. 27, 1872, the banker went to North Beach where he frequently swam, walked into the water and was later found floating face down. Most believed he committed suicide.