NGC G$1 1854 Type-2 Indian Princes Small Head Broadstruck AU55
Broadstruck and therefore expanded beyond its normal diameter.
The error occurred when the collar die was jammed below the surface of the reverse die, and was struck, and because there was no collar die in place, the coin expanded in size beyond it's normal diameter. Additionally, all or almost all of the reeding is missing from the coin's edge.
Broadstrikes are rare on gold dollars, and especially on Type-2 gold dollars!
AU55 with luster visible across much of the coin. There is moderate waviness in the planchet (likely the coin was slightly bent then corrected.)