How to get transcenden gems

Thiss gem. How to get it?

Kill the boss of a nightmare dungeon ( unlocks after normal dungeon 50 )
To enter you will need 3 nightmare gems, obtainable on normal secret dungeon,

Killum

Kill the boss of a nightmare dungeon ( unlocks after normal dungeon 50 ) To enter you will need 3 n...

Thanks bro

VHJhbkRhbg==

Thanks bro

I’ve collected well over 3 Nightmare gems but still can’t buy transcendent gems, any idea why?