Star Wars: Rogue One - 11 Biggest Unanswered Questions
5. What Is The Significance Of Jyn's Crystal?
The Question: Considering how much the movie focuses on the crystal given to Jyn by her mother, what exactly is its significance?
The Likely Answer: On a world-building level it shows how pervasive the Force is (we see Jyn briefly praying to the crystal) and on a story level it allows Jyn to come into contact with Chirrut.
Given the odd amount of focus Gareth Edwards places on the crystal, though, it seems highly probable it will have some significance in a future Star Wars movie, possibly ending up as the very crystal that ends up powering Rey's lightsaber...or something.
If not, then it's basically a colossally disappointing red herring.