Gabrielle Union -- My Fat, New Engagement Ring is Worth ...

EXCLUSIVE

Every kiss begins with ... an engagement ring that costs MORE THAN MOST PEOPLE MAKE THEIR WHOLE FRICKIN' LIVES -- if you're Gabrielle Union and Dwayne Wade, that is.

Dwayne popped the question Saturday night with an 8.5 carat cushion cut diamond ring (pictured below) made by go-to celeb jeweler Jason of Beverly Hills ... and TMZ has learned it goes for nearly 1 million bucks.

We're told Dwayne had been on the hunt for months for the stone of her dreams ... and his jeweler made 3 trips to Miami looking for the perfect jewel ... and third time was a charm.

Bravo.