The sequence of figures $F_1,F_2,F_3,\dots$ is defined as follows: $F_1$ is a single diamond. For $n\ge 2$, $F_n$ is formed by adding a new outer layer of diamonds to $F_{n-1}$. This new layer for $F_n$ consists of $4n-4$ diamonds. How many diamonds are there in figure $F_{25}$?