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 can injure the surface of the marble. Yet another effort to clean the marbles occurred in 1937–38. This time the incentive was provided by the construction of a new Gallery to house the collection. The Pentelic marble mined from Mount Pentelicus north of Athens, from which the sculptures are made, naturally acquires a tan colour similar to honey when exposed to air; this colouring is often known as the marble's "patina" but Lord Duveen, who financed the whole undertaking, acting under the misconception that the marbles were originally white probably arranged for the team of masons working in the