I stand under correction but I don't think they were completely dipped in melted gold as such but rather a solution with gold ions, which then gets deposited on the coin because of the cathode/anode thing.
Dipping in pure melted gold is expensive, and at least to my knowledge somewhat uncommon.
Thanks for helping us clarify this.
The coins were plated using a common process known as electroplating. This process uses electrolysis to deposit ions suspended in a solution on the coin (as explained above).
There are some pretty good descriptions online about how electroplating works, but if you have any more questions, please feel free to post here or send us a message.
Thanks