Bring the three gems to Urshi. She is the judge of this achievement. She will grant you the credit.
See #1 of Things That Are NOT Bugs
- Gem Level Requirements for Season Journey:
Urshi has to see 3 gems above the required level at the same time. If you used one as an augment or transferred to another character, it no longer counts. Once the 3rd gem reaches the requirement, it will complete but all must be available either equipped/inv/stash at the same time.