Marble (toy) Required" and "The Colbert Report". Currently, the world's largest manufacturer of playing marbles is Vacor de Mexico. The company makes 90 percent of the world’s marbles. Over 12 million are produced daily. Marbles are also made in China and may contain lead, arsenic, and/or cadmium due to the manufacturing process of old glass. Art marbles are high-quality collectible marbles arising out of the art glass movement. They are sometimes referred to as contemporary glass marbles to differentiate them from collectible antique marbles, and are spherical works of art glass. Collectible contemporary marbles are made mostly in the United States by
Elgin Marbles that "the Greeks were guilty of excessive cleaning of the marbles before they were brought to Britain." During the international symposium on the cleaning of the marbles, organised by the British Museum in 1999, curator Ian Jenkins, deputy keeper of Greek and Roman antiquities, remarked that "The British Museum is not infallible, it is not the Pope. Its history has been a series of good intentions marred by the occasional cock-up, and the 1930s cleaning was such a cock-up". Nonetheless, he claimed that the prime cause for the damage inflicted upon the marbles was the 2000-year-long weathering on the Acropolis.