This is one of my favorite pieces in the Penn Museum collection (where I now work). I love the crystal ball itself but this historical image of two girls in the Harrison Rotunda antechamber admiring it, is almost as amazing of a cultural treasure. The sphere itself is truly a spectacle of materials and optics. Official museum details:
Crystal Sphere with stand, China, 19th century, Qing Dynasty (1644-1912), Rock crystal, Silver, Penn Museum Object C681/ab. An ornamental treasure of the Imperial palace in Beijing, the crystal sphere was said to have been a favorite possession of the Empress Dowager Cixi (1836 -1908), the last effective Imperial ruler of China. The rock crystal originated in Burma and was shaped into a sphere though years of constant rotation in a semi-cylindrical cylinder filled with emery, garnet powder, and water. The forty-nine pond flawless crystal sphere is believed to be the second largest in the world. The stand in the shape of a wave was designed by a Japanese artisan.