The Romans, not unlike their predecessors, favored certain gems and metals over others. They also shaped gems and did do some intricate gold work, which paled in comparison to predecessors. As for gems, the winners are listed below in no particular order.
Cornelian
Cornelian has a long history of use in the Mediterranean. In fact, an almost perfectly round cornelian bead was dated to Late Minoan 1600 – 1100 BCE. Cornelian ranks a seven on the Mohs hardness scale which makes it a tough but carve-able stone. Its color may have also added to its popularity. Cornelian is often found on chain and bead necklaces and was popular stone for signet rings.

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1600 – 1100 BCE
©The Trustees of the British Museum
Emeralds
Emeralds, or smaragdi as they were called, were extremely popular before, during, and after Imperial Rome.
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Right: Emerald & Gold Necklace 1st century CE (?)
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Emeralds are a part of the beryl family. It’s an interesting family that includes emerald, aquamarine and a green variety which is often just called “beryl” but does not have the qualities of an emerald. To make matters more confusing, you’ll see the term “emerald beryl.” Emerald however is clearer and has a more distinct color which green beryl lacks. Green beryl was likely used as a less expensive alternative for emerald. Because of the natural crystalline structure of emerald it was often just cut and drilled. This shape gave credibility to its authenticity.

By Paweł Maliszczak [hardleo.com] – Own work, CC BY-SA 4.0
Not that stones weren’t shaped during this time. It was said that the best emeralds came from the “mines of Cleopatra.” Frederic Cailliaud visited and drew pictures of the old mines, the emerald mountains, the “Mons Smaragdus” on his expedition to Egypt in 1817.

An Example of “stretching your aureus”
In Imperial Rome, “stretching your aureus” by using cheaper alternatives was all the rage. In the below example, variscite (a phosphate mineral similar to turquoise) is mixed with emerald. The variscite is even shaped to mimic the look of emerald. the appearance of affluence by any means, real or fake was the name of the game. A vast change from the Republic when affluence was “un-Roman.”
Emerald & Variscite Gold Necklace 3rd century CE
The Metropolitan Museum of Art
Rock Crystal
Like cornelian, rock crystal has a long history of use. It is often shaped or polished and included with other components, such as gold. Given the preference for bright colorful stones it’s interesting that it kept its popularity into the Roman Empire.
Reproduction
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Right: Reproduction of a Parthian or Roman Rock Crystal and Cornelian Necklace
The original showed up in an auction house. Copyright laws forbids the use of the original image unless I want to shell out a lot of money.
Pearls
Pearls were among the most coveted item a woman could have in her collection, the most prized of of treasures. It can not be emphasized enough the desire and status of pearls in roman culture. They are most often found mixed with other stones in chain and bead style necklaces and very often found as earrings. Pliny the Elder, not necessarily a fan of jewelry was one of the few that commented (i.e. complained) about the use of pearls.

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“…and now, at the present day, the poorer classes are even affecting them, as people are in the habit of saying, that ‘a pearl worn by a woman in public, is as good as a lictor walking before her.’ Nay, even more than this, they put them on their feet, and that, not only on the laces of their sandals, but all over the shoes; it is not enough to wear pearls, but they must tread upon them, and walk with them under foot as well.”
Pliny The Elder
Gold
All that glitters is indeed gold. Gold was highly prized throughout the ancient world. The Greeks, Sumerians, Scythians, and many other cultures left behind simple to elaborate gold jewelry. And it wasn’t just in the Mediterranean. Gold has been found all over the world. The Roman jewelry that still exists today is overwhelmingly composed of gold or gold parts. The source of gold often, but not always, came from mines under horrid conditions. After it had been mined it was made into coins or jewelry. It has been theorized that some of the gold used for jewelry actually came from melted down coins. Even with coins being occasionally devalued by the Empire, by lowering the gold content, the purity of the gold Roman jewelry still has a purity between 90% (22k) & 99.9% (24k) (Ogden, J.).

1st- 2nd century CE
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Shapes
Contrary to popular belief shaping stones, beyond the usual round bead or cabochon, was prevalent. Sometimes they shaped them to look like other stones, such as emeralds (as discussed above), and sometimes it seems mainly ascetic. Popular shapes included: round, biconical (commonly seen with Amethyst and cornelian), box, disc, and melon.

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Granulation
Granulation in jewelry was quite popular in many cultures before the rise of the Roman Empire. Babylonian jewelers masterfully used this technique. According to The Met, “throughout the first half of the second millennium B.C. Similar gold disks with extensive granulation. However, it is far rarer in Imperial Rome.

Bottom Left: Babylonian Gold Pendant (1800 – 1600 BCE)
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