Diddy's got a keen eye for fine art, and his historic purchase of a Kerry James Marshall painting is a huge score for him and a bigger score for the artist ... according to a famous expert.
Brett Maly -- the fine art appraiser from "Pawn Stars" -- tells TMZ ... Diddy deserves a lot of praise for making all the right moves before dropping $21.1 MILLION on Marshall's 1997 work "Past Times" during a Sotheby's auction last week.
Maly says the combo of focusing on an acclaimed artist AND going after one of his most important pieces is a baller move ... and Diddy certainly made a splash.
As for that splash ... Brett tells us it should have a ripple effect for Marshall -- who's sold million-dollar paintings in the past -- by boosting his sales a few more million ... per piece. Not too shabby, especially since Puff's purchase already made him the most expensive living African-American artist.
Brett also seems to be on the same page as Diddy's son, Quincy Brown -- who says his dad's now a major player in the art world ... get used to it.