By the end of Oathbringer it becomes apparent that gemstones are playing a number of roles in the story, and hints that they have a greater significance in the Cosmere in general.
Consider:
Woah .. hang on ... think about it!
With that in mind, lets consider the Epigraph at the start of Chapter 42
hmmm ... putting it all together
There you go, my first contribution to the wild lands of Cosmere Theories ... i may be completely off track with this, but personally i feel there is something of merit in this line of thought.
I guess we will simply have to wait and in the immortal words of Brandon ... RAFO!