50 Cent said Floyd Mayweather is a FOOL for snatching up an $18 MILLION diamond watch -- but Paris Hilton tells TMZ Sports ... Fiddy is wrong, she actually likes it!!
"It looks like a watch that I have actually," Paris said at LAX.
Floyd claims he picked up the famous "Billionaire Watch" from a jeweler in Japan -- a watch that contains 239 huge diamonds!!!
50 Cent clowned Floyd for the purchase -- saying, "Man they done found the 1 fool in the world,dumb enough to buy that watch. LOL get the strap."
As for Paris, she defended Mayweather's spending habits, saying -- "It's a lot ... but I think he works very hard, he works for his money and he can buy whatever he wants!"
And, if you're curious how much Paris' diamond watch is worth ... it ain't cheap either!!