I was looking for information about this on the internet, and it says that the diamond award is for albums that have sold over 10 million copies, not 100 million. If this is the case then Fleetwood Mac definitely has at least one, because
Rumours has sold over 30 million copies.
Here is the site that gives the definition of a Diamond Award:
http://www.elvis-presley.ca/elvisriaa.htm