Take one last look at Nikki Reed's naked ring finger!  This photo was taken Sunday on the red carpet at the MTV Movie Awards in L.A. and verifies that former American Idol contestant Paul McDonald shelled out the cash to put an engagement ring on her finger!

Today's juicy scoop points back to her ring finger and this time Nikki allegedly tells E! Online that not only is her fiance 'the one,' but she has just gotten a tattoo of his name inked on her ring finger!

The couple met at the premiere of Red Riding Hood this past March ... leading them on this whirlwind romance.  No wedding date has been set.