Ronald Acuna Jr. will be the brightest All-Star during this week's festivities in L.A. ... thanks to his new $140k diamond chain!!
TMZ Sports is told Acuna -- a starting outfielder for Tuesday's All-Star Game after receiving the most votes among National League players -- copped a blinged-out nod to his aggressive style of play ... and it's incredible!!
The piece features Acuna's nickname, "La Bestia" -- which means "the beast" -- decked out in 12 carats of emerald-shaped VVS diamonds and 6 carats of round brilliant rocks ... and a gorilla enameled on top.
Gabriel The Jeweler tells us the chain is also made of 80 carats of VVS baguettes ... with the whole thing being worth a whopping $140k!!
We're told Acuna has plans to show off the bling when he takes the field at Dodger Stadium on Tuesday ... so keep your eyes peeled.