I was so hoping that Gauri would leave her diamonds behind when she left. Of course they were the last thing on her mind at the time.
What I was hoping would happen is this....as she leaves the house she realises that she's still wearing the diamonds and feels that they are a noose around her neck. As a sign of rejection, she decides to go back and give them to the very person who gave them to her.
Imagine this scenario...she's standing outside the bedroom door which Nikhila had not closed completely. Gauri overhears that there's one more aspect to the raaz and storms in and forces Shiv to spill the beans and once he did that, throw those diamonds at his face and walk out for good! Wow! That would have been something to see!!
As it is, she has those diamonds with her. Knowing her she won't sell them or anything. But she should return them out of a sense of self pride. Besides, her greedy sis-in-law might just take them for herself!