Bigger than a robin's egg but not quite as big as a deviled egg, the diamond earrings contain stones almost the size of that much publicized 69 carat ring Richard Burton gave Elizabeth Taylor. So who would have thought there were two women in the world owning almost identical pairs?

And who would have thought that if there WERE two such sets of similar earrings, that ones belonging to the deposed empress of Iran would be considered second-rate?

Sotheby Parke Bernet was busy calling journalists all over the world last Friday to deny a story that was running that day in Figaro in Paris which claimed that a $4.5 million pair of diamond earrings belonging to the late shah's widow were being auctioned off in Geneva on Nov. 15.

"The New York dealers are starting a ruckus," a Sotheby spokesman said last week. "Anything connected with Iran is tainted now, so we've been calling them to say 'Don't start feeling your nationalism now.' We need their participation if this sale is to be a success."

A formal denial was issued, stating that "These earrings do not belong and never have belonged to the empress. She is not the owner of any item in the sale."

The earrings consigned to Sothebys, a spokesman said, are of "D" color, which is "almost flawless."

Farah Diba owns an "almost identical" pair which she wore in 1971 during the 2500th anniversary celebration of the Peacock Throne in Iran.

But hers are "very well known in the trade to be of 'H' color" and "not as good as ours," the spokesman said.

From London, Graham Llewellyn, deputy chairman of Sotheby Parke Bernet Ltd., said that the earrings which are being sold this month "came from the estate of a deceased European lady and have been a part of her estate for some years and the sale was negotiated by me with her beneficiaries in September."

"I have never personally seen the empress' earrings," he said, conceding that photographs "probably do look like" the Sotheby earrings.

But Farah Diba's earrings are not as large, he said, "only 90 carats total as opposed to 120 carats."

If the Horschow's mail order catalog doesn't have enough snob appeal for you, there's one coming (but not in time for THIS Christmas) that should have all the richies ready to squiggle one zero after another in their checkbooks.

Rita Lachman, once married to the man who was the "L" in Revlon, has gone into partnership with a New York advertising executive to create a shop-by-mail concept for the woman who is so elegant that the phenomenally successful Horschow's looks like Sears Roebuck to her.

Lachman was the third wife of the late cosmetics czar Charles R. Lachman. Lachman's 21-year-old daughter, Charlene, is attempting to overturn her late father's will.

Lachman, who died in 1978 at the age of 81, changed his will on his deathbed to leave the bulk of his $30 million estate to his fourth wife, 38-year-old Jaquine de Rochambeau who had been Rita Lachman's secretary.

The legal challenge, now pending in the Appellate Division of the State Supreme Court in New York, has been joined by both the Metropolitan Museum of Art and Lenox Hill Hospital.

The Met was supposed to get Charles Lachman's collection of impressionist paintings, including works by Renoir and Degas and a very important Monet. The hospital had expected to get a $4 million bequest under a previous will.

Rita Lachman, who has no legal standing in the dispute over inheritance, is nevertheless following it with intense interest. She is taking notes for a proposed book that could be a best-seller.

Next to sex, there is apparently nothing most people like to read about more than money.

All that money in "Abscam" didn't flow one way.

While they were impersonating the phony Arabs, three FBI agents each received a $6,000 gold Patek-Philippe watch from the sting targets they were trying to bribe.

It seems that some of the "Abscam" defendants had learned how important the giving and receiving of gifts is in the Arab culture and didn't want the sheiks to consider them pikers.

Some defense attorneys have been making noises about using the existence of the watches to impugn the integrity of the agents.

A spokesman for the FBI says the $18,000 worth of watches have all been properly turned into the government.

But at least one defense lawyer is telling reporters that he is going to make an issue of how long the watches were worn before being surrendered.