Curved, Not Flat
The National Baseball Hall of Fame Commemorative $5 gold, $1 silver, and one-half dollar clad coins will have a shape such that the obverse is concave and the reverse is convex. While these will be the first curved coins ever minted by the United States Mint, it did produce the curved 1973 Roberto Walker Clemente Congressional Gold Medal in honor of the late Pittsburgh Pirates star right fielder.
Specifications
Composition: 90% gold, 10% alloy
Diameter: 0.850 inch (± 0.005) 21.59 mm (± 0.127)
Weight: 8.359 grams
Overall Height: 0.141 inch (± 0.005)