In my Fantasy world I thought it would be interesting to have a creature whose eyes would be precious gemstones or crystals. I want to understand how that could be possible, and if any ramifications could come of this. The world is not highly magical, so a non-magical solution is desired.
For instance, I know that there are clams which can produce pearls by slowly accumulating minerals and polishing them into a smooth pearl. I am thinking it could work in a way similar to that.
The creature would be born with tiny eyes made of only a very little bit of some mineral. This creature would live in an area rich in this mineral, and it would be accumulating this mineral in its diet over a long time these minerals would deposit in the eyes to make them grow.
Now the problem is how would the creature be able to see with these gemstone eyes?
I thought maybe it could work like a lens or something similar, with some organ behind the gems that catches the light and the gems or crystals refract it or something.
I am curious if this is something that is possible at all, and if so - how would it impact this creatures sight?