A few years ago, a Bulgarian woman working in her vineyard turned over a clod of dirt. The sun hit the dirt and it glittered back. She had found the first Preslav Treasure.

By the end of the day, her spade had turned up 150 pieces of jewelry. A lavish gold and cloisonne' enamel necklace, decorated with images of the Virgin, birds and flowers, and hung with rock crystal and pearls, was the most important piece. But others in the find were wonderful: enameled plaques from a diadem; earrings, some of them so large they would have to be suspended from a crown rather than the ears; pendants; rings; gold ornaments for clothing; pieces of a headdress; and 15 Byzantine silver coins. The jewelry, experts say, was likely from the 9th or early 10th century, though the coins were mid-10th century.

The second Preslav Treasure was more carefully hidden. Its 13th-century owner hollowed out a limestone and filled it with, among other things, gold and silver coins, gold and silver earrings, bracelets, a ring, a seal, belt ornaments, an icon, two crosses and a walnut-shaped bead necklace.

These jewels are in an exhibit of 88 pieces of jewelry from the Preslav Treasures and three Bulgarian treasure troves, opening to the public today in Dumbarton Oaks' Byzantine collection (1703 32nd St. NW). The exhibit, organized by the Smithsonian Institution Traveling Exhibition Service, will remain through Dec. 28, and then go on to other museums. The show marks the first major loan exhibition at Dumbarton Oaks.