Two elegantly dressed men, who said they were from India, stuffed a $100 bill into a jewelry store manager's breast pocket yesterday - and then walked off with a $17,500 diamond.

The man who came up $17,400 short in this transaction was Patrick H. Stager, manager of the Harris Jewelry Co. at 1101 F St. NW. The $100 tip was for Stager's helpfulness in showing the two men an assortment of uncut diamonds, but Stager later agreed that the tip may have been a diversion.

"They definitely palmed the diamond," he said unhappily. "How or when they did it, I don't know."

D.C. police said that the two purported Indians appeared to be professional flimflammers. And Stager, with the benefit of hindsight, noted that their accents waxed and waned a good deal during the time he spent with them.

"They came in and asked to see some unset diamonds," said Stager. "And I took some diamonds out to show to them . . . but during the time they were looking at these diamonds and talking to each other, I got the impression that they weren't exactly happy."

So Stager had a French and Italian speaking assistant attempt to determine the source of his customers' unhappiness. "She came out and she spoke with them in Italian and they told her that I was not showing them large enough diamonds."

Stager then brought out a tray of bigger and better diamonds for them - including the 2.69 carat stone that later turned up missing. His customers seemed much happier with this new assortment, Stager said.

"You have been very helpful," said one of the men as he peeled off a $100 bill and stuffed it into Stager's pocket.

Along with a modest wad of American currency, the man had a stack of what he said were Swiss francs. He told Stager that he would have to exchange the francs for dollars in order to buy the diamonds he had chosen.

Stager put the diamonds away and offered to escort both men to a nearby bank with a foreign exchange window. But when they insisted on going to a different bank instead, the manager told them he would have to go back to his store while they completed their errand.

It was on his return to the store that Stager noticed that the diamond was missing and concluded that he had been bamboozled.

"If one steals enough, one dresses very well and has large sums of money," said Stager.

The suspects were described as dark-complexioned men in their 40s with black hair who spoke broken English when they wanted to.

After calling the police, Stager said he notified a number of area jewelers to be on the alert for the two men. "Techniques similar to this are used from time to time," commented Thad Webster of the Jewelers' Security Alliance.