Being the first black to serve on the Virginia Supreme Court is not the only "first" in John Charles Thomas' career. A year ago, the young attorney, then 31, was the first black to become a partner in major law firm in Virginia.

In leaving the blue-chip Richmond firm of Hunton and Williams, Thomas will give up what is likely a considerable salary for the $64,000 earned by each of the seven members of the state high court. As he said jokingly at a press conference today, he will also have to give up "shopping in my blue jeans"-- a reference to the strict rules of decorum followed in the cloistered world of Virginia's high-court justices.

"What's important is that he is flatly qualified, regardless of color," said W. Taylor Reveley III, his law firm's managing partner. "He will certainly bring to the court intelligence, considerable presence and immense enthusiasm."

His accomplishments as a litigator capped an academic career also marked by distinction. At the University of Virginia Law School Thomas was a member of the Raven Society, reserved for the academic elite. As an undergraduate in Charlottesville, where he majored in American government, he was on the Dean's List of Distinguished Students.

Born in Norfolk and a graduate of public school there, Thomas apparently turned down lucrative jobs to stay in Virginia, Reveley said. Since moving to Richmond, Thomas has been active in local and state civic affairs. He was a supporter of Gov. Charles S. Robb -- and last year married Pearl Walden, a member of Robb's staff -- and served in 1976 as cocounsel to the Carter-Mondale campaign in Virginia.

Thomas' expertise in civil and commercial law -- an area in which he represented a broad range of the firm's corporate clientele-- will help the Virginia Supreme Court "provide more precedence, more guidance for lawyers in that field," said law partner Alan Rudlin.

Rudlin and others would not predict whether Thomas will play an activist role on a court known for its conservatism and its strict interpretations of state law. "As to whether Thomas will be a strict constructionist or an activist, I don't have any sense whatsoever," Rudlin said.

An avid backgammon player, a gourmet cook and a music lover with an extensive collection of jazz records, Thomas is regarded by friends as a young man with a big future. "He is one of the most intelligent people I've ever met," said Springfield lawyer and Democratic activist Steven Stone. "I see him with not only a bright judicial future, but a political one. After all, this appointment is only for 12 years."