"Jewels" being decorative things and not necessarily stones, it appears the jewels here are metal, gold and silver, though it lists coral and amber as part of it.

Ancient temple filled with gold and silver jewels discovered in Greece

Archaeologists excavating a sanctuary honoring the ancient Greek goddess Artemis have announced they discovered a significant number of structures, as well as plentiful relics, including gold and silver jewels.

A "monumental building in the heart of the sanctuary" was first found in 2017, according to a recent social media post from Greece's Ministry of Culture. Another temple was found in 2023. Excavating this second temple turned up "rich relics" and jewelry, the ministry said. Other excavations found buildings from the ninth and eighth centuries B.C.

The excavations are conducted annually by a group of Swiss and Greek archaeologists, the Ministry of Culture said in a news release. The research project began about 15 years ago, the ministry said.

A bonus link at the bottom of that story says an ancient aqueduct was uncovered along with a few coins.