Traumatic optic neuropathy (TON) refers to an acute injury of the optic nerve secondary to trauma. The optic nerve axons may be damaged either directly or indirectly and the visual loss may be partial or complete.
In Minecraft, emerald ore is very hard to find and is found in small deposits in the Extreme Hills biome. You can usually find emerald ore between 13 and 31 blocks below the ground and close to lava. So if you see a pool of lava in the Extreme Hills biome, that is a great place to start mining downward.
Originally, the Ruby was meant to be the material for Villager trades. However, they were later replaced by the now used Emeralds. Ruby was supposed to look like an Emerald but more circular. Like the Quiver and Skis, Ruby still exists in the Minecraft files.