NFL's NaVorro Bowman: I'M GETTING HITCHED ... Check Out The Ring

San Francisco 49ers linebacker NaVorro Bowman is calling it quits ... on the single life ... preparing to tie the knot with his long time GF in a star studded April ceremony ... TMZ Sports has learned.

We got NaVorro leaving Avianne & Co. Jewelers in NYC and when we asked what kinda bling he was copping in there and he showed us ... by flashing a massive rock on a lovely lady's hand.

That lovely lady is Mikale Ferguson ... a celebrity stylist who Bowman's been with since high school and is marrying in a private garden ceremony at Caesars Palace in Las Vegas this spring.

The guest list is dripping with celebrities ... Vernon Davis, Glenn Dorsey, Dashon Goldson, and other NFL stars are expected to attend ... with more names likely to pop up.

Looks like another linebacker is creeping up on you, Russell.

10:14 AM PT -- We're told the ring is 10 carats and has a $175,000 price tag!!