Bling!

Talk about putting your money where your mouth is ... pro athletes are now spending THOUSANDS of dollars to pimp out their mouthpieces with diamonds and gold ... TMZ Sports has learned.

In fact, NBA star Nate Robinson is part of the "pimp your mouthpiece" movement -- and recently picked up a $5,300 customized mouthguard that's chock-full of real gold foil.

The man behind the piece is Dr. Michael Wright of "The WrightGuard" ... who tells us high-end custom protection is becoming a major trend with athletes in a variety of sports ... from hoops to football and boxing.

In fact, Wright says he was recently approached by a NFL star who's playing in the Super Bowl (Wright says he can't reveal the player's ID) ... who requested a mouthpiece with some massive diamonds flanking the front.

"The Super Bowl athlete brought his own diamonds," Wright says ... "I don't know how many carats, but they were huge."

Wright says his mouthpieces are just as functional as they are flossy -- and says he has a special 3-layer process to make sure the gold, silver and/or diamonds are sealed in a way that it won't harm the user.

Wright says he's gotten some crazy requests from some of his athletes -- some people want team logos others want their Twitter handles -- and says team reps sometimes oversee the process to make sure the mouthpiece complies with uniform standards.

With so much customization at the pro level (mouthguards, cleats, etc) ... keep an eye out for the platinum diamond-encrusted jockstrap in the future.

"Modern Family" star Sofia Vergara is engaged to marry one of the hottest guys in town ... so why is she hiding her massive engagement ring?

"True Blood" star Joe Manganiello popped the question over the holiday weekend after just six months of dating (and Sofia only broke up with her other fiancé less than two months before that).

Vergara was spotted at the airport with her ring turned around so nobody could see it.

The ring is rumored to be at least 10 carats ... who's gonna miss it?

He might be one of the toughest guys in the NBA, but Sacramento Kings player Reggie Evans has a soft spot for his kids ... as evidenced by the adorable chain he rocked around NYC yesterday.

Evans -- who was in town to play the Brooklyn Nets -- headed over to the Barclays Center with several diamond-encrusted pictures of his 4 kids.

C'mon ... that's cute and you know it.

Evans was also rocking out a pair of fancy Louboutin boat shoes ... $1,200 a pair.

Drake's expensive jewelry collection is coming back to bite him in the ass -- a famous jeweler is suing him over a $50,000 owl pendant ... claiming Drake illegally made knockoffs of it for his friends.

The jeweler Baden Baden Inc. (owned by designer Michael Raphael) filed the lawsuit, claiming Drizzy hired the company to make a custom diamond-studded platinum owl pendant back in January ... and paid $49,204.

Then in June ... BB claims gold duplicates of the pendant started surfacing on Drake's Instagram.

According to the lawsuit, BB claims Drake took its original design, copied it, and handed out the knockoffs to his pals.

Baden Baden is suing for copyright infringement, demanding unspecified damages, and asking the court to force Drake to hand over the owl copies.

One potential sticking point -- Drake's been using the owl logo for years ... it's the freakin' cover of his 2011 mixtape.

As we previously reported, Raphael is also suing Drake for unpaid styling services.

In a move that says, "F You, I'm too rich to steal your crappy diamonds" ... rapper Tyga has posted a photo of the contents of his jewelry box hoping to publicly shame the guy accusing him of thievery ... and at the very least, it's damn impressive.

We broke the story ... Tyga is being sued by Jason of Beverly Hills -- a famous jeweler who claims Tyga never paid for $91k in diamond and gold jewelry back in 2012 (a pantheon timepiece and a chain).

But hours after we published the story ... Tyga went to Twitter and posted a photo of his finest 27 gold pieces ... with a message that reads, "Shout out to my Jeweler @emitthejeweler !!!!! I don't f*k with #bitchn**gas @jasonofbh."

Translation -- I'm too rich to steal your crappy diamonds and I've got a better jeweler than you anyway.

As for the jewelery at the center of the lawsuit ... those 2 pieces were not on display in Tyga's Instagram pic.

As if the world wasn't bad enough ... smokin' hot Paulina Gretzky has dashed the hopes and dreams of men worldwide ... by getting ENGAGED to pro-golfer Dustin Johnson.

Paulina announced the terrible news on Instagram Saturday -- posting a pic of the giant diamond rock on her ring finger, captioned "Never been happier."

The couple has only been dating since early 2013 -- but, really, who wouldn't lock that down?

Now, a final farewell, to Paulina's almost-hitched assets ...