Armand Hammer had been a millionaire as long as anybody could remember when around the age of 60 he got into oil.

Everybody knows what that does to the handbooks, so that 10 years later Hammer didn't have to check his balance when he set about collecting the art of a Frenchman named Daumier. Art critics and students agree that Daumier is one of the greatest political cartoonists of all time.

"I've left a standing order to buy any original Daumier on the market regardless of price," Hammer said last night at the Corcoran Gallery of Art where a selection from his collection goes on public view until Dec. 18.

Chuckling a little, the chairman of Occidental Petroleum Corp. continued: "They say I've run the price up about five times what they're worth, but I want this collection to be the greatest."

Few among the 170 or so black-tie dinner guests of Hammer and his wife Frances would have disagreed. Flanked by Corcoran President David Lloyd Kreeger and wife, Carmen Kreeger, the Hammers received in an upstairs gallery before everyone regrouped later over filet of sole, roast veal and pears Julia in the candelit atrium -- courtesy of the Hammers.

While Hammer basked in his newest philanthropic role as member of the Corcoran's board of directors, his wife stood demurely by, her emerald, diamond and sapphire necklace reflecting polite stares.

Polly Guggenheim Logan, who prides herself on being able to tell at a glance if jewels are genuine, decided, "It's always nice to assume they are -- so few wear real ones any more."

Catharina Biddle murmured her approval though she confessed she likes simple little Calder-type necklaces. "Liv (her husband, the chairman of the National Endowment for the Arts) gives me these," she said, touching a diamond lavaliere at her throat, "and I certainly don't turn them down."

Guests included most of the Corcoran's board of directors, the French ambassador, Sens. Howard Metzenbaum (D-Ohio), Jennings Randolph (D-W. Va.) and Jacob Javits (R-N.Y.), the J. Carter Browns representing the National Gallery of Art and the Joseph Hirshhorns representing the lery of the same name.

The dinner celebrated Hammer's $1,150,000 gift last spring to he Corcoran which enabled it to open its doors free of charge to the public. Funds also provide for renovation of the gallery's auditorium.

"In the last six months," Kreeger told the crowd, "attendance has tripled. The rumor I get is that Carter Brown and Joe Hirshhorn are quite worried."