TWENTY-FIVE years ago this fall the Postal Service adopted a European idea and, in the process, came up with some of the most popular stamps ever issued in the United States -- the Christmas stamps.

The first year, it was a single four-cent stamp, a small red and green one, picturing a holiday wreath, candles and the lettering "Christmas, 1962." And it was an overwhelming success.

Soon the public was clamoring for more and the Postal Service began issuing two holiday stamps each year, one with a contemporary theme and the other with a traditional theme.

This year's stamps, to be issued October 23, will have a special significance for Washington area collectors. The contemporary stamp was designed by James Dean of Annandale and the traditional stamp features a 16th-century painting by Giovanni Battista Moroni, "A Gentleman in Adoration Before the Madonna," which hangs in the National Gallery of Art.

A measure of how popular the Christmas stamps have become is the number that the Bureau of Engraving and Printing produces. This year's production run calls for about 1.5 billion of the two stamps, compared to the typical run of 160 million for a commemorative stamp.

That means being selected to design a Christmas stamp is a special honor. Dean, whose stamp features decorative red, blue and gold Christmas tree balls, is a design coordinator for the Citizens' Stamp Advisory Committee, the panel that picks stamp designs for the Postal Service.

Bradbury Thompson of Riverside, Connecticut, another design coordinator, helped prepare the traditional stamp, which will feature the 14th work of art from the National Gallery on a U.S. Christmas stamp. Thompson's adaption of the painting features a Madonna and child and carries the lettering "Christmas" and "Moroni, National Gallery."

First-day ceremonies for Dean's contemporary stamp will be held in that capital of contemporary America, Disneyland, in Anaheim, California. Disney cartoon characters will be on hand to push the Postal Service's "Mail Early" campaign.

The traditional stamp will debut in Washington in ceremonies planned for the National Gallery's East Building that promise a more traditional event.

Those upside-down candlestick stamps that got several Central Intelligence Agency employees in trouble must have prompted many people to look more closely at their stamps.

That's at least one explanation why two more U.S. stamp errors have surfaced in recent weeks.

Neither of the latest errors is likely to be as valuable as the $1 candlestick stamps, which some collectors say could be worth as much as $115,000 each.

New Jersey dealer Jacques Schiff, who has handled the sale of some of the candlestick stamps, says both of the new errors are stamps that apparently missed one of their colors as they passed through the Bureau of Engraving's presses.

In one case, a sheet of the recent U.S.-Morocco commemoratives slipped out of the bureau without any lettering at all, yielding a stamp that bears only the central design, a red arabesque copied from a palace in Fez, Morocco.

This stamp is classified as a "missing color error" and that should place its value in the $400 to $600 range, Schiff said in an interview. He said he acquired a sheet of 50 of the stamps from an individual he declined to name who bought them in southern Massachusetts.

The other error, also a missing color, was found in Des Moines, Iowa, where two sheets of the new stamps celebrating the art of lacemaking turned up lacking the lace. That part of the design was supposed to be applied to a blue background through an engraving process, a technique used only once before on a U.S. commemorative.

According to the Associated Press, an Iowa collector sold the stamps for "at least $1,000" and they have since been resold to collectors on the East Coast.

Because both these stamp errors appear to have been the products of equipment errors, they are not as valuable as the candlestick stamps.

It's the human factor that makes a stamp error rare, Schiff said. "That's what's earthshaking."

First-day cancellations of the Christmas stamps will be available through November 22. Collectors supplying their own stamped covers should mail them to Customer- Affixed Envelopes, Christmas Stamp, Postmaster, Anaheim CA 92803-9991 for the contemporary stamp and to Washington DC 20066-9991 for the traditional stamp.

The Postal Service will affix stamps to envelopes for 22 cents each for up to 50 covers. These should be requested from: Contemporary Christmas Stamp, Postmaster, Anaheim CA 92803-9992 or Traditional Christmas Stamp, Postmaster, Washington DC 20066-9992. Combination covers with both stamps can be obtained from either city for 44 cents each.

Bill McAllister is a member of The Post's national staff.