minecraft-src/data/minecraft/recipe/emerald_from_smelting_emerald_ore.json

{
  "type": "minecraft:smelting",
  "category": "misc",
  "cookingtime": 200,
  "experience": 1.0,
  "group": "emerald",
  "ingredient": "minecraft:emerald_ore",
  "result": {
    "id": "minecraft:emerald"
  }
}