SPOILER My Theory On We Crystals

There are 4 (actually 6) crystals. Yellow, purple, red and green. It kind of looks like they are associated with elements. If yes, we are missing the white/air crystal. I have 2 theories why there is no white crystal:
1.they are not associated with elements
2.there is no place where they would fit. what i mean is that location of the crystals is associated with they're color and possibly element. yellow is on desert, purple in tundra, red inside a volcano and green in jungle, but where would the air crystal fit? actually, anywhere in wynn province or ocean. sky island would be good but it's in gavel, and this is WYNN excavation.

Spoiler: 6 crystals i mentioned

so i mentioned that there are actually 6 crystals. the 2 other crystals i'm talkint about are the light and dark crystals seen in the ancient dungeon in WE site D. if you carefully read the dialogue in this quest you will notice that someone mentions light and darkness

sorry for making this very unclear and painful to read but i'm currently on my mobile and it's nightmare to make threads here, i will rework it once i get access to my computer

 

the light and dark crystals aren't actually formal crystals, are they?

also, they are most likely not related to the elements, considering it's purple and not blue. however, in one of the puzzles in site d, the purple crystal is represented using blue stained clay. this is most likely an accident or something that needs to be fixed. anyway, I doubt that they are associated

 

What about the crystal seen in 1000 meters under? It's confirmed that the corpotation that funded the professor was infact WynnExcavation (even though that crystal was associated with the Void).

And as qraq already stated, the light and dark crystals aren't actual crystals, the part with the puzzles is just a way of telling the lore of Light and Darkness.