Adamas (5e Equipment)
From D&D Wiki
Adamas is a material left behind by celestials. Sometimes when they depart the material plane, traces of this substance can be collected and forged into weapons, armor, and other items. An item forged from this material can usually be imbued or blessed with a limited amount of celestial power. Weapons imbued by a celestial typical deal radiant damage. Armor can protect its wearer from radiant damage or shine light in an area. Other items' effect vary.