Last Wednesday, November 28, Adele reached a milestone that's increasingly impossible these days because of declining album sales. Her sophomore album, the chart-crushing 21, surpassed 10 million copies sold and officially became certified diamond. This ends a drought for the industry that was approaching nine years in length.

It seems very likely that albums going diamond on a somewhat frequent basis is a trend that will never return. But back in the '80s and '90s? Forget about it. Everyone from boy bands to country groups to deceased rappers were rolling in the deep dough at a level not seen in the past decade.

So as a means of celebrating Adele's ongoing success and highlighting her new triumph, we took a look back at every album that's gone platinum. It's a roundup that reveals, among other things, that Garth Brooks is a very, very rich man. Click below to begin.

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