The tomb scene, which is the third scene of Act 5, tells us that Juliet is in a state of desperation (as is anyone who is about to commit suicide). First consider her words:
What's here? A cup closed in my true loves hand? / Poison, I see hath been his timeless end. / O churl! drunk all, and left no friendly drop / to help me after? (5.3.166-169)
Almost immediately Juliet is longing for a drop of the same poison that killed her lover to secure her own death. As the scene goes further, Juliet become even more desperate and, as such, even more metaphorical:
O happy dagger! / This is thy sheath; there rest, and let me die. (5.3.173-174)
Here Juliet begins by giving the dagger human qualities, therefore using personification. Further, she uses herself as a profound metaphor. Juliet is the sheath into which she thrusts the dagger, killing herself. Could there be a more desperate scene? In your contemplation, consider this fact: the time Juliet awakens to the time when she dies is only 35 lines which is less than one page. In addition, the time Juliet figures out Romeo has perished to the time when she dies is only ten lines! That is desperation for you!