Gabrielle Union -- Takes MASSIVE Ring to Lakers Game ... With Bodyguards

Gabrielle Union -- the future Mrs. Dwyane Wade -- took her brand new million dollar 8.5 carat diamond ring out in public yesterday ... but not without some serious hired muscle to keep it safe.

Gabby and Ring arrived to the Staples Center in L.A. ... flanked by private security ... to watch their man dominate the Kobe Bryant-less Lakers.

Funny, Kobe knows a little something about expensive jewelry ... in fact, he may have bought the most expensive ring out of ALL the NBA players ($4 million) .. except his wasn't a "Will You Marry Me" diamond -- it was a "FORGIVE ME!" diamond.