Marble (toy) conventions. Additionally, many glass artisans produce art marbles for the collectors' market only, with some selling for thousands of dollars. Marbles are made using many techniques. They can be categorized into two general types: hand-made and machine-made. Marbles were originally made by hand. Stone or ivory marbles can be fashioned by grinding. Clay, pottery, ceramic, or porcelain marbles can be made by rolling the material into a ball, and then letting dry, or firing, and then can be left natural, painted, or glazed. Clay marbles, also known as "crock marbles" or "commies" ("common"), are made of slightly porous clay, traditionally
Elgin Marbles for public exhibition overseas, which is provided for in the 1963 Act. Another argument for keeping the Elgin Marbles within the UK has been made by J. H. Merryman, Sweitzer Professor of Law at Stanford University and co-operating professor in the Stanford Art Department. He has argued that the Marbles are now established as a significant element of Britain's own cultural history, as "the Elgin Marbles have been in England since 1821 and in that time have become a part of the British cultural heritage." He has also argued that if the Parthenon were actually being restored, there would be