Lea Michele Shows Off Her Engagement Ring and Her Fiance

Lea Michele knows NOTHING sweetens up your cup of coffee like a massive diamond ring on the hand that's holding it.

The "Glee" grad was strolling around NYC Tuesday with her new treasure -- as in her fiance, Zandy Reich ... the guy who gave her the OTHER treasure.

We know you're wondering, so ... it's a 4-carat elongated radiant cut diamond. Lea and Zandy announced their engagement last weekend. They've been dating since last summer, when Zandy managed to bust out of the friendzone ... they were pals before the hookup.

The groom-to-be is president of the clothing company AYR -- and his bride-to-be is obviously very proud ... of his taste in jewelry.