1 - 1/8". After extensive research this American made sulfide marble is attributed to being made by J.H. Leighton and Co. glass factory, producing melted pontil marbles in the late 19th century. The ceramic inclusion, the sulfide, is a thin disk, with the iconic blue color unique to Akron made ceramics with "ghost" lettering, manufactured by the American Marble & Toy Co. in Akron Ohio. Samuel Dyke was in the political novelty business and had many associations with William McKinley, included being appointed to represent the United States as Ambassador at large for trade in 1898. Being a double sided marble, one side of the disk reads: McKinley and Protection and the other side reads: Sound Money and Prosperity. This rare very cross-collectible American Sulfide has great surface condition, surface shows as created cold roll marks which I like to see. Condition (9.5). Size 1 - 1/8".