The curse of the Hope Diamond was first given credence by Paris jeweler Pierre Cartier -- or so the story goes -- to entice Washingtonian Evalyn Walsh McLean into buying the largest known deep-blue diamond. She did purchase it, for $180,000, a princely sum in 1911.

Today the fabulous jewel spins in its new, impregnable case in the Harry Winston Gallery at the Smithsonian's National Museum of Natural History.

Legends whirl around it like the 16 pear- and cushion-shaped diamonds set in platinum that encircle the now 45.52-carat blue gem.

The curse began, it is said, in India in 1642, when Jean-Baptiste Tavernier, a French gem merchant, smuggled a 112.5-carat rough blue diamond out of India and sold it to Louis XIV, who had it cut to 67.5 carats. At 80, Tavernier was torn apart and eaten by wild dogs. The Sun King died of smallpox, or perhaps gangrene. Louis XVI didn't wear the diamond, but his queen, Marie Antoinette, did. Both were beheaded during the French Revolution.

Before she bought the diamond, Evalyn Walsh was lucky. "Father Struck It Rich," her frank, fascinating 1935 memoir with Boyden Sparks, tells about her eventful life, including the source of Thomas Walsh's fortune -- the Camp Bird gold mine in Ouray, Colo. He built a magnificent mansion, now the Indonesian Embassy, at 2020 Massachusetts Ave. in 1902.

The bad luck her book reveals began in 1910 with her marriage to the wealthy and wanton Ned McLean. On their honeymoon in Paris, Cartier showed them the Hope Diamond and told its tales. Some months later, Cartier reset it to Evalyn McLean's taste and left it on her dressing table for a weekend. Mrs. McLean was perhaps as intrigued with the colorful stories as with the blue gem. "Objects unlucky for others are lucky for me," she often told a close friend, author Hope Ridings Miller. The Cartier sales contract had an unusual clause: "Should any fatality occur to the family of Edward B. McLean within six months, the said Hope Diamond is agreed to be exchanged for jewelry of equal value." Ned McLean's mother died soon after its purchase, warning her daughter-in-law that the diamond was indeed cursed. So she had it blessed in a church. As the minister consecrated it, a huge tree across the street fell with a mighty crash as if struck by lightning.

Mrs. McLean also told Mrs. Miller that "the luckiest thing about it is that if I ever had to, I could hock it." She did indeed pawn the diamond many times. She was perpetually in debt to caterers who served her parties, including one for 2,000 socialites at her home, Friendship. Idaho Sen. William Edgar Borah looked around her ballroom and declared, "This is what brings on revolutions." She also ordered 1,000 sandwiches for World War I veterans during their 1932 Bonus March and generously entertained wounded World War II soldiers from Walter Reed Army Hospital.

When it wasn't in hock, Mrs. McLean kept the diamond close at hand, tucked under the sofa cushions. At lavish parties, she often wore it together with the 94.8-carat Star of the East and the 31.26-carat McLean Diamond. She wore the Hope during delicate surgery, friend Alice Roosevelt Longworth said. She wore it to races, while swimming and on an Arctic fishing trip with mystery writer Mary Roberts Rinehart.

Mrs. McLean's Great Dane Mike wore the Hope. Her great-grandson Joseph Gregory said his grandmother teethed on the diamond. (Gregory, a Nashville "image maker," said he's soon bringing out a perfume named for Evalyn Walsh McLean.)

The McLeans' 9-year-old son, Vinson, Gregory said, was carrying the diamond in his pocket on the day he evaded his keepers, ran into the street and was killed by a passing car. The diamond was unharmed. His mother, returning from the Kentucky Derby, related that "my father, dead nine years, suddenly appeared and said, Vinson is dead.' "

Meanwhile, Ned McLean -- more of a curse even than the diamond -- cavorted with shady ladies, entertaining President Warren Harding's Cabinet in the notorious "I Street White House," also called the "Love Nest." Once, in Palm Beach, McLean shared his whiskey with a trained bear, and took it to a house of ill repute. Two women were badly mauled. Even after Mrs. McLean had him committed to a Baltimore sanitarium, Ned continued his playboy life, dancing the hokey-pokey with author Zelda Fitzgerald, F. Scott Fitzgerald's wife.

Gregory said his grandmother, also named Evalyn McLean, at 19 married 57-year-old Sen. Robert Reynolds, a North Carolina Democrat who had courted her mother. In 1947, the younger Evalyn died of an overdose of sleeping pills. Less than a year later, her mother died at 60 of pneumonia. Both women, Gregory said, died wearing the Hope Diamond. "When she died, J. Edgar Hoover took charge of it and put it in the FBI safe."

Two years later, jeweler Harry Winston bought most of Mrs. McLean's jewelry. He donated the Hope Diamond to the Smithsonian in 1958. The Winston Gallery, funded by his son's foundation, leads into the new Janet Annenberg Hooker Hall of Geology, Gems and Minerals. Ronald Winston, president and CEO of the Harry Winston Co., now values the Hope at $200 million, "the most expensive object that can be held in one hand."

The senior Winston, his son said, made fun of the gem's evil reputation and liked to sit in his favorite chair (with built-in safe) and fondle it.

Yet, Ronald Winston noted, "my mother never wore it." CAPTION: D.C. socialite Evalyn Walsh McLean shows off her beloved Hope Diamond in an undated portrait.