A few ideas for T4 gems:
-Choose a feature that can be activated a limited number of times per day. You increase the number of uses by one.
-You gain a feat or equivalent feature.
-Your visual acuity improves greatly, either gaining a special quality, or an appropriate bonus to detect others
-You gain an intelligent personal companion, if you already have one, it gains a notable boost to its abilities
-A distant, and wealthy, relative has named you as an heir in his final will, but has a task for you to complete before you can claim your share of the inheritance.
-Whispers invade your dreams, hinting at the location of a long lost artifact, waiting for someone worthy of claiming it.
-You are recognized for a great service to a nation, earning a medal, award, or title, and the fame (And infamy, where appropriate) that goes with it.
-You gain a remarkable form of personal transportation.
-You have made a powerful personal friend, he is willing to grant aid from time to time.
-You have made a powerful personal enemy, he will seek his revenge one way or another
-A sizable bounty has been offered for your head by a rogue state.
-False rumors have spread about your character concerning personal connections with powerful figures. You have an easier time getting what you want, as people try to gain your favor, but the truth will come out eventually.
When you wake up in the morning a small wooden box is besides your head. On the outside are curious markings. When you open it something positive happens to you. (The Dungeon Master then has the choice of what happens).
Where are the random gems acquired? A random encounter in the Town, while on patrol? After successful completion of a job?