Starcrystal Fragments are crafting materials that are dropped by the Final Bosses of each Heroic Mode area, and are used to create Starcrystals when you collect 8 Fragments in one area. The color of the fragments corresponds to the color of the element of the Heroic Mode armor.
In order to get the 6 materials needed to craft the armor, players must defeat the final boss of each map area in Heroic Mode. Formerly, this required always using a "power attack", but that is no longer required. Also, 8 total Starcrystals were required to craft the Heroic Mode armor, but as of November 21st, 2016, only 6 are now required.