Sheik Allal al-Fassi, whose in-laws are members of the Saudi Arabian royal family and who is accused of trying to sell a stolen $1.2 million emerald-and-diamond ring to an undercover FBI agent, has skipped bond and left the country, the U.S. Attorney's Office said yesterday.

U.S. District Court Judge Barrington D. Parker issued a bench warrant for al-Fassi's arrest after the 21-year-old sheik, who was ordered in January not to leave the country, failed to show up yesterday for his arraignment on a charge of interstate and international transport of stolen property.

Prosecutors said al-Fassi somehow managed to leave the country and is believed back in Saudi Arabia, which has no extradition treaty with the United States.

"We know almost to a palace where he is," said Assistant U.S. Attorney Noel A. Kramer. But the U.S. government has no extradition agreement with Saudi Arabia, and Saudi Arabia is unlikely to voluntarily extradite al-Fassi, Kramer said.

Still, Kramer said, "This matter is not going to be dropped . . . now he has another offense, violating the provisions of his release." That offense carries a maximum penalty of five years in prison and a $5,000 fine.

Parker shook his head from side to side as al-Fassi's attorney, Richard Ben-Veniste, explained that he had received a call yesterday morning from al-Fassi. Ben-Veniste said he assumed al-Fassi was in Saudi Arabia, since he was with his wife, who remained in that country.

"How did he get out of the states--by diplomatic pouch?" the judge asked Ben-Veniste, because al-Fassi has no passport. U.S. Magistrate Jean F. Dwyer ordered al-Fassi's passport held at the Dec. 27 hearing at which he was released on bond.

"I don't think he's small enough to fit in a diplomatic pouch," Ben-Veniste replied. How he left the country "didn't come up in the conversation," Ben-Veniste said.

The U.S. Customs Service usually does not require that U.S. or foreign citizens leaving the country show a passport. But Vern Jervis, spokesman for the U.S. Immigration and Naturalization Service, said airlines frequently ask their passengers to show a passport before departing "to make sure they'll be able to get them inside the country where they're going."

Al-Fassi has been concerned about the health of his wife, who is to give birth in two weeks, Ben-Veniste said. "He told me he did not mean any disrespect to the court, but he could not leave his wife at this time," Ben-Veniste told Parker.

Al-Fassi is the brother of Mohammed S.A. al-Fassi, a flamboyant figure who last year gave the District $50,000 for its summer jobs program for youth and has been involved in celebrated legal battles.

According to court papers, on Dec. 24, Allal al-Fassi offered to sell a 22-carat emerald ring surrounded by 16 diamonds and valued at $1.2 million to FBI undercover agent Michael Hartman in the Washington Hilton Hotel. Hartman was posing as a businessman "looking for investments."

The ring al-Fassi allegedly tried to sell matched the description of a ring reported stolen last May by the jewelry firm Harry Winston Inc. of New York. The company reported the ring missing after a jewelry showing it had conducted in the Miami home of al-Fassi's brother-in-law, Saudi Prince Turki Ben Abdul Aziz.

By failing to appear at his arraignment, al-Fassi also forfeits the $25,000 cash bond he had posted before his release. Prosecutor Kramer said the U.S. government may yet catch up with al-Fassi because he frequently travels to England and France, countries that have extradition treaties with the U.S. She said the U.S. Attorney's Office intends to notify authorities in those countries.