| Diameter |
| 1870 – 1967: 29.72mm 1968 – to date: 27.13mm |
| Weight |
| 1870 – 1910: 11.62g 1910 – 1967: 11.66g 1968 – 2000: 8.10g 2001 – to date: 6.90g |
| Composition |
| 1870 – 1919: .925 silver, 0.75 copper 1920 – 1967: .800 silver, .200 copper 1968 – 2000: nickel 2001 – to date: .9325 steel, .0475 copper, .0200 nickel |