Credit: Kevin Mazur/; Mark Davis/PictureGroup

New bride Megan Fox was doubly radiant during a surprise appearance at Monday's VH1 Do Something Awards in Los Angeles -- where she wore both a new engagement ring plus her wedding ring, which she's been wearing since her surprise June 24 nuptials to Brian Austin Green.

Fox's new engagement ring replaces the one she misplaced on a Hawaiian beach just hours after Green, 36, proposed June 1.

According to jewelry and style expert Michael O'Connor, Fox's engagement ring replacement features a 3 carat radiant cut center; "the platinum set diamond collar around it adds significant size and sparkle to ring," O'Connor tells The engagement ring is worth about $80,000, he estimates.

The wedding ring, O'Connor tells Us, is a platinum and diamond eternity band with an approximate price of $20,000.

"Since they are both set in platinum, there's definitely maximum sparkle going on," O'Connor adds of Fox's bling.

The couple first got engaged in November 2006 but called it off February 2009 -- finally tying the knot at a hush-hush Hawaiian ceremony attended only by Green's 9-year-old son, Kassius.