Shine Bright like a Gemstone

Unlock Criteria: Have the Diancite

Location:

Description: After picking up on some sort of psychic energy from one of your Mega Stones, Mimi got up and headed out. Where could Mimi be off to?

After you have received the Diancite, go to the Looker Bureau. When there, you can talk to Mimi and Emma will notice that Mimi is reacting to your Diancite and Mimi will leave. Your task is to follow Mimi.

Mimi will start by leading you around to a food truck where you learn Emma is hungry by hearing her thoughts, presumably with Mimi's help. From there, you continue to chase Espurr through the city

Description:

Eventually, Mimi leads you to a rooftop in Magenta Sector 8 filled with Mega Crystals. Soon after, two Carbink and a Diancie will appear and Emma suggests that you cath the Diancie.

Diancie Level 70

OT: Yours ID: Yours Hold Item: None

Any Nature. Date of Receiving Magenta Sector 8. Met at Lv. 70

Diamond Storm Moonblast Stealth Rock Draining Kiss

After catching the Diancie, Emma will note it looks reminiscent of the Anistar Sundial and mention that AZ and Sycamore had a theory that Mega Evolution came to be when the Ultimate Weapon irradiated certain stones, and the reason why more Mega Evolutions have been discovered is because the Ultimate Weapon was fired again 5 years ago.

Emma then mentions that AZ mentioned that while searching for Floette, he went to Hoenn and saw a phenomenon he believes was the start of Mega Evolution.