MLB's Fernando Tatis Rocks $200k 'El Nino' Diamond Chain During All-Star Week

Fernando Tatis is shining bright like a diamond at the MLB's 2021 All-Star Week ... rockin' a massive 'El Nino' diamond chain --- worth $200k!!

The San Diego Padres shortstop's nickname is 'El Nino' ... and you may have spotted Tatis rockin' the ice during the Home Run Derby in Denver on Monday -- and the jewelry is amazing.

TMZ Sports has learned that the pendant -- featuring a little boy's face -- is filled with 25 carats of VVS emerald diamonds ... and the specially made Hermes chain holds 75 carats of VVS diamonds!

That's a total of 100 carats -- worth 200 racks!!

And, Tatis isn't the only All-Star reppin' his alias in some new bling ... Atlanta Braves' Ronald Acuna Jr. got a diamond 'El Abusador' pendant featuring his team's logo.

It's infused with 100 carats of VVS diamonds and is worth $175K!

Even though the right-fielder tore his ACL last weekend, he'll still be in Denver showin' love -- and maybe we'll catch him sportin' the new ice!

We're told that both chains -- made by Gabriel the Jeweler -- were designed and inspired by their close friend Nick Drbal.