LONDON.- For six months, a team at the British Museum has been working with police to recover hundreds of engraved gems and other items of jewelry that museum officials say a former curator stole from its store rooms.

The team has also been planning an exhibition.

“Rediscovering Gems,” occupying a room by the British Museum’s grand entrance through June 2, includes dozens of the tiny artifacts known as cameos and intaglios — 10 of which are recovered items.

Art dealers who bought the stolen items — some of which date back to ancient Rome — have returned 357 treasures to the museum, said Aurélia Masson-Berghoff, a curator who is leading the recovery team.

Although more than 1,000 items are still missing, and could take years to locate, Masson-Berghoff said her team was hopeful that those could be recovered, too. The new exhibition was part of the museum’s efforts to be transparent about the thefts and its efforts to retrieve the items, she added.

During a recent tour of the show, Claudia Wagner, the museum’s senior research associate for gems, said that the jewels had long been underappreciated. The tiny artifacts — often less than a half-inch tall — are hard to discern in natural light, making them easy to ignore, she added. In the exhibition hall, small torches are provided so that visitors can see them properly.

Some of the museum’s previous Greek and Roman curators had preferred to focus on bigger and more renowned artifacts like statues and vases, Wagner said, which could explain why many of the cameos and intaglios were uncataloged before the thefts.

On the tour of the show, Wagner and Masson-Berghoff discussed the origins of these precious gems, their uses in ancient times and how they once entranced Europe’s art connoisseurs. These are edited extracts of that conversation.

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Glass Intaglio of Bacchus

WAGNER: The first engraved gems were what’s called intaglios — where the design is carved into the gem or glass. They were used as seals, so people would push them into wet clay — the equivalent of writing your signature.

They were invented in Mesopotamia, but it’s the ancient Greeks who make them into their own art form, and because the Greeks were so interested in mythology, you immediately have all the gods represented. If you look very, very closely at this tiny little figure, he has an ivy wreath in his hair. That’s because this is Bacchus, the god of wine.

The gem is so small — only a centimeter or two — because you wore it as a ring.

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Glass Cameo Depicting a Winged Cupid

WAGNER: As well as intaglios, there are cameos, where the design is carved in relief. This is a pretty good one of Cupid — a lovely boy with wings. A lot of them were gifts, and when you look at this, you do have the feeling it was for a darling lover.

Cameos and intaglios were first engraved on precious stones. The Romans only learned how to make glass gems in the first century A.D. Glass was new and exciting for them and it meant that you could mass produce these items. It was still a really complicated and difficult process to melt glass into a mold, and you find a lot of glass gems sit in very expensive gold mounts.

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Glass Cameos Depicting the Three Graces and a Sea Nymph

WAGNER: In the Renaissance, people became completely obsessed with carved gems, because everyone was looking back at how great the classical artists were.

Collectors also loved gems because they were undamaged. If they bought a classical statue, it’d be missing its arms, or its nose. But these cameos were complete, so collectors were seeing the image as the Greeks and Romans did. Neither of these gems were stolen or recovered — unlike the other items — but they have been included in the exhibition to show the beauty of the tiny images, and the difficulties in making these masterpieces in glass.

MASSON-BERGHOFF: Michelangelo is thought to have copied a cameo of Augustus and used it in his design for Adam in the Sistine Chapel. His Adam has the same pose. The craze for gems really started in the Renaissance.

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A Cameo of a Bearded Man

WAGNER: In the 18th century, collectors going on the Grand Tour around Europe also became fascinated by antiquity, and some became huge gem collectors.

Because so many people were trying to buy these objects, engravers started making a lot of fakes. It was a huge scandal, because suddenly everyone thought, “We can’t distinguish between what’s ancient and what’s new anymore.”

This cameo is a fake. We have no idea who it’s meant to be. Usually they’re meant to be intellectuals, but you can see this isn’t quite right: He’s not one of the great philosophers you might recognize from antiquity. And the texture is also different to other cameos: it’s much smoother.

With the help of our chemists, we can now distinguish what is Roman glass and what isn’t.

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A Glass Intaglio of a Beardless Roman

WAGNER: These gems are very difficult to exhibit, because they’re so small. This one is barely 2 centimeters in length. In the exhibition, we’ve got an enormous copy of this one on the wall so people can see all the details clearly. It coveys its beauty.

This article originally appeared in The New York Times.