Now, you should know that there are several different types of Mandela coins. The biggest differential between them is the time in which they were released to the public. In 2008, the Nelson Mandela 90th birthday coin was released. Today, this is considered to be one of the rarest coins of all. As the name implies, this coin celebrates Mandela’s 90th birthday. The 2000 Millennium Coin is also very rare. This coin was released as a way to show respect to Mandela when he retired as State President. The 1994 Inauguration coin celebrates Mandela’s inauguration as President.