It is hard to know by just one look if the boobs are fake or real.
.....Unless you hold it:-)
Thanks to Cosmopolitan PH, they've got a list of Ten Best Celebrity Boobs.
Marian Rivera is top on the list, her boobs has the right size and looks real firm.

Michelle Madrigal's boobs is amazing. At the FHM 100 sexiest party it looks even sexier.
Angel Locsin's body is every man's luck. Though it has undergone changes, the way it looks is even better now. Darna's juggling boobs is phenomenal.
Cristine Reyes is gifted with natural great boobs. Now that she is the girlfriend of Derek Ramsay, I must say that it was really a great choice:-)

I so love that Gretchen Fullido's boobs is included. I admire her a lot.
Here's the complete list of Cosmo's Best Boobs
Best Natural Boobs: Marian Rivera Best Boobs Boosted by Workouts: Michelle Madrigal Best Boobs With Staying Power: Angel Locsin Best Boobs on a Thin Woman: Cristine Reyes Best Enhanced Boobs: Ellen Adarna Best Reporter Boobs: Gretchen Fullido Best MILF Boobs: Jennylyn Mercado Best Boobs on an Athletic Body: Solenn Heussaff Best-Kept Boobs: Karylle Best Boobs on a Curvy Woman: Angelica Panganiban
Good Job Cosmo PH for making this list.