If the coin is lit from above, lines become visible in the zeros.
When lit from below, 500円 becomes visible in both zeros.
Hidden in the numbers are the letters N-I-P-P-O-N
The two 'P's
The 'O' and the 'N'
On the back, the letters NIPPON are also printed, only much smaller
You can see the 'O' and two 'P's on the right hand side
These letters are about the same height as a human hair's width (.1mm)
