Redstone Gem pillar is a pillar that contained a redstone with Gem in it. The Redstone Gem Pillar was first seen in The Haunting: Legend of The Herobrine Part 3 and hasn't been seen since then.
In The Haunting: Legend of The Herobrine Part 3, Drake and Armen got close to the Redstone Gem Pillar and got a severe headache from it. The Pillar had the ability to give people severe headaches. A Redstone Gem Pillar or simply a Redstone Gem can cause great pressure on you and on your head. It is so powerful that it may even cause death. The only solution to get rid of the headaches and pressure is to drink the Red Healing Potion.