It is springtime in the National Geographic Explorers Hall, and summer and fall as well. The museum is blooming with tulips and orange blossoms, pansies and cornflowers all at once. Such can only happen in a fantasy world, of course, in this case the fantasy world of Peter Carl Faberge, jeweler to Russia's tsars. His lilies of the valley sprout from gold moss, their pearl blossoms edged with rose-cut diamonds.His cactus is two shades of jade, gold-veined. And since every flower garden needs wildlife, Faberge carved snails and rabbits and frogs of jade. In fantasy worlds, everything can glitter; Faberge's desk calendars are diamond encrusted; on his glue pots and card cases he entwined gold into serpents, carved thumb rests from rubies and sapphires. The National Geographic has gathered 143 Faberge treasures for this exhibit, including four jeweled, hinged, enameled, carved, painted, etched, inset Easter eggs that could have been created just to have a worthy use for the word fabulous.

Objects of Fantasy by Peter Carl Faberge, National Geographic Society's Explorers Hall, 17th and M Streets NW, November 4 through February 23. Open Monday through Friday, 9 a.m. to 6 p.m.; Saturday, 9 a.m. to 5 p.m.; Sunday, 10 a.m. to 5 p.m. Free. $857-7000.