Controversial Hills co-stars Heidi Montag and Spencer Pratt are engaged. 23-year-old Pratt proposed to Montag, 20, on Tuesday night at a resort and spa in Santa Barbara. “She said ‘yes.’ She’s over the moon!” says a source. Pratt bought a diamond-encrusted platinum ring with a pink stone the previous day with Montag in two, according to a source. “She was trying on tons of them and they looked really happy!” says a witness.