A 23-year-old Los Angeles man was sentenced here yesterday to five to 15 years in prison for his part in the September 1984 armed robbery of $550,000 in jewelry and watches from the Neiman-Marcus store in Mazza Gallerie, which police said was the largest robbery in the District's history.

Ralph Bryant, who prosecutors said took part in a multimillion-dollar, nationwide stolen property ring, was described by U.S. District Judge Gerhard A. Gesell as "a street hoodlum [who] came in here to rob."

Two men had previously been sentenced in the case, and Bryant's brother Winzell has been charged. Another member of the group, Ivory Stowe of Los Angeles, has pleaded guilty to transporting the jewelry to Los Angeles and is awaiting sentencing.

FBI officials said the key figure in the ring was Saied Kalimi Aframian, 29, the owner of a secondhand jewelry store in downtown Los Angeles, who was convicted there late last year of receiving stolen property. According to an FBI affidavit, Aframian paid $80,000 in cash for the Neiman-Marcus jewelry. The robbery took place on Sept. 25, 1984, when two men, including one with a handgun, entered the Neiman-Marcus department store at 5300 Wisconsin Ave. NW. The robbers ordered clerks at the jewelry counters to place an assortment of expensive rings, bracelets and watches into a shopping bag, specifying which items the pair wanted, the FBI said.

In February, Gregory Barnes of Los Angeles pleaded guilty to the same charges of armed robbery and interstate transportation of stolen goods. He was sentenced to four to 12 years in prison by District Judge Barrington D. Parker.

In sentencing Bryant yesterday, Gesell rejected a contention by attorney Richard Stern that Bryant had "problems" with marijuana and cocaine. Gesell said there was no evidence that Bryant was addicted. He said Bryant "hadn't done a lick of work since he dropped out of school in 1981 and turned to a life of crime."