A mini-battle began shaping up in Congress yesterday, no over the usual issues like the Panama Canal or energy taxes, but over Balkan jewelry.

At issue is President Carter's decision to return to Hungary a 1,000-year-old relic - the Crown of St. Stephen, which symbolizes Hungary's religions, cultural and national identity. The American government has held the crown since the end of World War II.

But some Senate conservatives, led by Sens. S. I. Hayakawa (R Calif.), Bob Dole (R-Kan.) and Jesse Helms (R-N.C.), object to the return of the crown, saying that it confers legitimacy on a Communist-dominated state.

Dole introduced a statement for the record to that effect on Hayakawa's behalf yesterday, and added that he failed to understand why the U.S. government should approve the status of a regime that came to power as a result of Soviet military might. Dole said he was also distressed by the timing, because Carter's decision came 21 years to the week after Soviet tanks quelled the Hungarian uprising of 1956.

Rep. Mary Rose Oakar (D-Ohio), whose district includes the largest concentration of Hungarian-Americans in the country, was also upset by the Carter decision. Earlier this year she introduced a bill of block the return.

She released the contents of a letter she wrote to Carter Thursday night, in which she said the crown has as much significance to the Hungarian people as the Bill of Rights and the Constitution do to Americans.

"We will be true to its heritage," she said in the letter, "and to the brave Hungarians who entrusted it to us at the end of World War II, only by refusing to return it except to a government of Hungary that is independent, and that possesses the legitimacy conferred by the consent of the people."

Secretary of State Cyrus R. Vance is expected to deliver the crown to Hungary before the end of the year. State Department officials have said that Carter decision was based on a desire to improve relations with Hungary.

Sen. Joseph R. Biden Jr! (D Del.) recently visited Hungary as chairman of the Subcommittee on European Affairs of the Foreign Relations Committee and favors returning the crown. He said in a statement yesterday that the legitimacy of the Hangarian state was settled in the 1960s by the United Nations and the United States, when ambassadors were exchanged.