If you're spawning this for Trial of the Magians, you can prevent Colorful Abyssite from changing colors by holding onto your Grey Abyssite after it changes.
Buy a new Clear Abyssite and either upgrade it in a different zone or only go to spawns that say "The Grey Abyssite resonates feebly".
After you get another Colorful Abyssite, only go to spawns that say "The Grey Abyssite resonates softly".
If you see "The Grey Abyssite resonates solidly", move far away and try elsewhere.