I have got all the gems from first and second pyramid.
1st pyramid: no gems in 1 and 2
2nd pyramid: no gems in 7 and 11
In 3rd pyramid I got 17 gems - couldnt find any in 3, 6, 10, 15 and top left.
In 4th I have found gems in 1 and 3 - still stuck in 6
- are you sure you been in all the hidden rooms? I missed one first time I played and then couldnt move on.