Buy RS3 Ring of forging
The Ring of forging is a handy item for training Smithing in RuneScape 3. When you wear it, you only need one iron ore to smelt an iron bar instead of two. This means your ore lasts twice as long, so you can make more bars and gain more Smithing experience from the same trip.
The bonus works when smelting iron ore at a furnace or when using the Superheat Item spell. It even works with ore stored in an ore box. Each player can smelt 140 bars with the ring before it disintegrates. The charges stay with your account, not the ring itself. If you wear Varrock armour, you may smelt two ores at once while only using one charge.
The ring is made by casting Lvl-3 Enchant on a ruby ring, which needs level 49 Magic. It is tradeable and noteable, and it weighs almost nothing at 0.006 kg. It has no combat stats, so it is purely a skilling item.
If you want faster and cheaper iron bars for Smithing training, the Ring of forging is a smart pick for any RS3 player.