Jerry Zipken stood in one doorway of the drawing room, with its pale green 18th-century boiserie paneling from a chateau in Amiens, and shouted across the fine French furniture to former ambassador Guilford Dudley's wife, Jane.

"First wife," challenged Zipken.

"Second wife," laughed Mrs. Dudley.

A placard identified the magnificent room and its contents as a gift to the Detroit Art Institute from Mr. and Mrs. Ernest Kanzler.

The second Mrs. Kanzler is a friend of Zipken's and Mrs. Dudley's and a lot of other people invited to lunch at the museum yesterday.

But it turned out to be the first Mrs. Kanzler, just as Zipken had guessed, who had given the room everyone admired so much.

The luncheon, for "The Group" from California who are the Ronald Reagans' closest friends, was arranged by one of their own who had once lived in the Grosse Pointe suburb of Detroit: Anne Johnson, who used to be married to Henry Ford II.

Mrs. Johnson, now married to Los Angeles attorney Deane Johnson and associated with the West Coast operation of Christie's auction galleries, wanted to show off the magnificent cultural landmark to which she and her family have contributed so much.

"The Group" got a special tour. And they were easy to spot in the midst of the polyester around them.

Anne Johnson arrived wearing strawberry-sized ruby-and-emerald earrings, surgar-frosted in two rows of engagement-ring-sized diamonds. With her simple silk dress she wore a long, diamond-studed gold chain.

Her Grosse Pointe friend, Mrs. Allan Shelden III, who will entertain "the Group" at a buffet tonight before the convention session, wore amethyst silk and and an amethyst ring as big as a pecan.

The jewerly, even at 11 o'clock in the morning, sets "The Group" apart, even among other affluent Republicans.

Mrs. Earl E. I. Smith, wife of the one-time ambassador to Cuba, wore a huge diamond "9" on a chain.

"My husband said he didn't want to give me a swelled head by giving me a "10," she explained. "I understand you can buy them in novelty stores now, but not in diamonds. I'm glad mine came set in diamonds."

Mrs. David Murdoch, whose husband owns Pacific Holding Co. in California, wore a diamond ring that was both almond-shaped and almond-sized. At the throat of her black silk shirt she wore a carved crystal agate set for her by Bulgari in a frame of diamonds.

Among other holdings, the Murdochs own Stair & Co., the New York antique store that they spent three years persuading MCA's Jules Stein to sell to them. They just got back from a two-week buying trip in England and Scotland, not only with new marchandise for the store, but with new treasures for the store, but with new treasures for a Beverly Hills house that was the subject of a 20-page cover story in Architectural Digest last month.

For the enormously wealthy Murdoch, the trip to Detroit this week was a homecoming of sorts. He started in business there with a short-order lunch stand when to got out of the Army at the end of World War II.

Husbands as well as wives came to the luncheon.

All the men wore "Reagan Pose" buttons, stamped with stars like a sheriff's badge. When "Social Moth" Zipken -- friend of all the wives -- saw that the black-and-beige political pins exactly matched his fastidious black-and-beige attire (beige suit, black-and-beige tattersall shirt with black knit tie and tasseled black loafers) he wanted one, too.

Zipken was planning a special dinner party for the wives last night at the London Chop House -- Detroit's most exclusive restaurant, despite its name. l(CBS board chairman Bill Paley was turned away on Sunday night when he turned up without a reservation.)

In addition to wives of "The Group" -- whose husbands are almost all members of the California delegation -- Zipken had invited others of his favorite "ladies" from New York, including the wives of Walter Cronkite and William F. Buckley.

One of "The Group," Hollywood producer Jack Wrather, had been "watching television in a bar" before the luncheon.

"From Washington, I saw my old roommate from the University of Texas, Bob Strauss, and my Sigma Nu fraternity 'Little Brother,' Lloyd Bentsen," he said, "talking about the election, and I said to myself, 'I'll be seeing you soon.'"

Buy Wrather, who owns hotels at Disneyland as well as the rights to "lassie," says he isn't "making a hotel reservation for the inauguration or buying a house in Washington yet."

"If the Russians decide they want Jimmy Carter to be reelected, they can free the hostages . . . move out of Afghanistan . . . anything can happen."

Others in "The Group" included attorney William French Smith, real estate tycoon William Wilson, steel magnate Earle Jorgensen, and Dart Industries chairman of the board Justin Dart.

Mrs. Dart was actress Jane Bryan. According to Bonita Granville Wrather, "Bette Davis said she was the most gifted young actress on the silver screen in the 1940s."

Mrs. Dart wore a necklace that looked like a museum piece. Hung from a chain of antique beads was a papier-mache Egyptian scarab made by two San Francisco designers, Alex & Lee.

Actress Ginger Rogers, who isn't a member of "The Group" but was invited because she is in town performing in "Anything Goes," wore no jewelry except four inexpensive enameled Indian bangles.

She also wore short white gloves, bottoned with tiny white pearl buttons, and didn't take them off until she sat down to eat her shrimp salad.

Rogers is only one of a number of VIP's in town for reasons unrelated to to convention this week who had trouble finding a place to stay. When she couldn't get a hotel room, someone who was going on vacation lent her an apartment.

Barry Manilow, whose manager said he didn't even know the Republicans were going to be in town, ended up borrowing a mansion from other absentee owners.