In the rarefied world of imperial craftsmanship and collectible objets d’art, few creations command awe like the legendary Fabergé eggs. This December, at Christie’s London, the celebrated Winter Egg—a singular masterpiece originally commissioned in 1913 by Tsar Nicholas II—will go under the hammer once again. Experts anticipate it could fetch more than $27 million, positioning it to become the most expensive Fabergé ever sold.