The JAR Light in the Darkness is very bright

There are a number of things Joel Arthur Rosenthal, the reclusive Bronx-born, Paris-based “Fabergé of our times” more commonly known as JAR, who is also the only living jeweler to have a solo show at the Metropolitan Museum of Art, will not do.

He will not, for example, advertise his wares. He will not wholesale them. He will not allow people to walk in off the street and see them. He will not sell them to anyone he has not personally approved. He will not negotiate price. He sells what he wants, when he wants, to whom he wants. He hates publicity, public appearances and public statements, especially if they reveal anything personal.

But this particular historical epoch can inspire even the most reticent of us into unexpected activities and make even the most purely emotional acts resonate with political implication.

Or so it seemed this week when Mr. Rosenthal appeared in Rome at the opening of the first joint exhibition of the Jewish Museum of Rome and the Vatican. Titled “Menorah: Worship, History, Legend,” it includes 130 objects from the first century through … well, Mr. Rosenthal, who created his first piece of Judaica as well as the only piece of commissioned original art for the exhibition. Not to mention the first object he has made that was not meant to end up in the hands of an individual (collectors like Lily Safra, Madonna and Lisa Airan) but, as he said, “to be seen out there.”

“It was unexpected,” he said of being a part of the exhibition. “I have done all I could to shield myself from what’s going on in the world” — and this show, with its message of unity, was a clear (if gentle) statement about what is going on the world. “But I was confident because of what it is and where it was going.”

When Mr. Rosenthal first heard of the exhibition, organized in part by a friend, Alessandra di Castro, the director of the Jewish Museum in Rome, he had been impressed by the idea, he said — by the surprise of these two institutions transforming a growing dialogue into action during a period of global isolationism — and had wanted to help out. His first idea was to make a few small items for the gift shop: a mezuza and a Star of David pendant. Because of time pressure, however, he couldn’t, so Ms. di Castro suggested he make a piece for the show itself instead.

“I thought he would never do it,” she said. “But it inspired him for a mysterious reason I don’t know. He wouldn’t tell me what he was making.”

What he was making — as a gift for the Jewish museum and in five weeks, an uncharacteristically fast turnaround for Mr. Rosenthal, whose average piece takes three months to six years, according to the craftsman Laurent Bouissiere — turned out to be a three-dimensional living branch of a menorah. It was made in bronze and aluminum (with a touch of gold), and shaped like the limb of an almond tree in bloom with multitudinous pink enamel flowers and a central bud glowing with a pavé mix of white and gold diamonds, blue and violet sapphires, and pink rubies, one petal lit with stones like a flame. When she saw it, Ms. di Castro said, “I was very moved.”

Mr. Rosenthal recalled: “I grew up going to shul on Rosh Hashana and Yom Kippur, and with the Hanukkah candles. I remember being terrified at my bar mitzvah because you had to sing, and my voice was cracking.”