Benzino is begging Althea Eaton for a second chance after she caught him cheating -- and she's open to it, but he will have to pay dearly ... in diamonds!

We got the ex-"Love & Hip Hop: Atlanta" stars outside Catch, where Benzino tried pleading his case to Althea asking for her forgiveness. It's sooo humiliating to watch, but sooo entertaining.

Althea eventually names her price, but not before Benzino has to choke down a full crow with a side of humble pie. On the other hand ... it looks like they arrived together, and MIGHT be leaving together. So, maybe Benzino's already working his way out of the doghouse?

Good luck, bro.

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