Their purchases: A diamond bracelet and ring, both from the 1970s, a source confirms to PEOPLE.
The couple spent about an hour at the unmarked shop, located on a cobblestone street near the Via Condotti, Rome’s poshest shopping area.
The tiny shop – about the size of two phone booths – specializes in 1950s to 1970s era jewelry. (It has very little jewelry on display, but there’s a huge built-in safe.)
Timberlake and Biel – who came to the shop on a recommendation – asked the shop assistant to empty the safe, and Biel proceeded to try on nearly every piece.
One particularly interesting piece? A 17th century necklace. When Biel found out how old it was, Timberlake started serenading her with a song from the soundtrack to Easy Virtue, her upcoming period film.
“I could tell they had very refined taste because they asked about the history of all the jewelry,” shop owner Nicola Boncompagni tells PEOPLE. She added that the couple seemed “shy but in love.”
Biel chose not to wear any of the purchases immediately – preferring to have the jewelry delivered to their hotel.
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