As we can see the certain jewels are exclusive to certain maps (Reng'ol) only. And those have value. Also some jewels( water, nature, diamond) drops more in tombs and mines along with many greens, blues pinks and locked. And it takes up inventory space so fast.
And also from an economic point of view some jewels ( water, nature, diamond..) doesn't hold its value( Keep in mind that jewels are reusable ). In my opinion all jewels should retain around same value. Some jewels value is high and some are dirt cheap doesn't make sense.
As a suggestion restrict jewels dropping from main maps only and drop something else like vanity ingredient? to craft vanity? from tombs and mines.
This will encourage PUGS to run maps instead. Also there are many newcomers into the game leveled to 41 instantly. This will also encourage them to grind old maps and make some gold during grinding the old maps and new maps.

Thanks for reading