Floyd Mayweather -- Drops $685,000 ... In NYC Jewelry Spree

Not like he needs it, but Floyd Mayweather just bought EVEN MORE insane jewelry ... dropping $685,000 in a fancy NYC jewelry shop ... TMZ Sports has learned.

Mayweather just walked out of Pristine Jewelers with several members of his Money Team crew.

Our sources tell us ... Mayweather bought more than a dozen pieces of jewelry for himself and his posse.

Mayweather had hit up the store Thursday and talked about his spending plans with the store owners -- before returning on Friday afternoon to purchase the goods.

It's not the first time Floyd's gone on a high-priced jewelry spree ... he spent more than $500k on a bling run back in May.

#ItsGoodToBeRich