The Peruvian ambassador and the State Department official peered through the glass case at a flat disk of silver, a remnant of the long ago Inca civilization.

Some discussion ensued of what it might have been used for, neither man quite sure. Around them circulated a noonday crowd of a couple of hundred guests, reporters and photographers who had come to the embassy to see the 700 artifacts of Peruvian art, some dating to 1000 B.C., that were removed from that country and are now being returned to the Peruvian government.

They lingered over other items of gold and silver in the case. Ambassador Fernando Schwalb told Thomas O. Enders, assistant secretary of state for inter-American affairs, the well-publicized story of the Smithsonian curator of Latin American archeology, Clifford Evans, who had been asked to examine the artifacts when they were first brought into this country by a New York art dealer: "He was called by the authorities to look at these items and he was so shocked." Evans suffered a heart attack and died hours later.

Enders turned to Schwalb, a look of incredulity spreading across his face. "Oh?" he said. "That's terrible."

The return to Peru of more than $1.5 million worth of artifacts--some of which were seized from the New York dealer in January 1981 as he brought them into Dulles Airport from Lima, Peru--was celebrated yesterday as a sweet victory for Peru and for U.S. Customs officials.

"They're the real heroes of this," Enders said of Customs officials who are now legally empowered, by a bilateral agreement between Peru and the United States, to seize works of art illegally removed from Peru.

"I hope," said William von Raab, U.S. commissioner of Customs, "now that this action has been taken, this will be a sign to those who would attempt to plunder graves and rob Peru of its heritage that the U.S. Customs and the U.S. government are vigilant."

"Some people think we are in the business of witch-hunting for collectors," said Schwalb. "That's not true. We are against illicit traffic."

Von Raab said that the flow of that traffic has lessened. "I can't say it's completely stopped," he said, "but . . . certain dealers have said they haven't seen much of these things since the case."

Credit was also given to those who conceived of the art. "It's ultimately the Peruvians who had the creativity to make them," said Enders, "and that is what we honor here."