4-Star Evolution Gem

A diamond containing the purest power of the Astral, which can be used to promote a Senshi's Star Rank.
You can give it to a Senshi via the "Give Gifts" button in the Senshi interface, and can raise their Star Rank up to Four-Star at most.
You must have a One-Star Senshi before you can give a gift, and you can only raise one Star Rank at a time. After promotion, the original Star Energy will be reset to zero.