You've spent hours mining at Y-level -59. You finally have a stack of diamonds. Now you want to put them into your Smeltery because you saw a cool tool build online, but the GUI just sits there. Nothing happens. It’s frustrating. Most players assume that because you can melt iron, gold, and copper, you can just toss a diamond in and get "Liquid Diamond."
Honestly, that’s not how the mod works.
If you’re trying to figure out how to melt diamonds Tinkers Construct style, the first thing you need to accept is that, in the base version of the mod, diamonds aren't a liquid. You cannot melt them into a molten state using a standard Smeltery and lava. It sounds weird because Minecraft logic usually dictates that anything can be processed, but Tinkers' Construct (especially in 1.16.5, 1.18.2, and 1.20.1 versions) treats diamonds as an "modifier" or a "material upgrade" rather than a castable liquid metal.
Let’s get into the weeds of why this is and what you actually do instead.
The Diamond Problem: Why They Don't Melt
Tinkers’ Construct handles materials in two distinct ways. You have your "Castable" materials—think Iron, Cobalt, Manyullyn—and your "Part" materials like Wood, Stone, and Diamond. In modern versions of Tinkers (Tinkers' Construct 3), diamonds are used via the Tinker Station or Tinker Spirit (if you have addons), not the Smeltery.
You don't melt them. You apply them.
If you try to put a diamond into a Smeltery fueled by lava, the heat isn't high enough anyway. Lava provides a specific heat level in the mod's internal code. Even if a modpack does allow melting diamonds, lava usually won't cut it. You'd need Blazing Blood or Molten Pyrotheum from a mod like Thermal Expansion to reach the required temperature. But again, in "Vanilla" Tinkers, there is no recipe for Molten Diamond. It simply doesn't exist in the base mod’s config files.
Wait, I Saw Someone Do It?
If you saw a YouTuber pouring liquid diamond into a tool part cast, they are playing a heavily modified version of the game. Modpacks like Enigmatica, All the Mods, or SkyFactory often add "PlusTiC," "Tinkers' Complement," or "Moar Tinkers." These addons rewrite the rules.
✨ Don't miss: Wordle July 2: Why This Specific Puzzle Still Trips Up the Pros
In those specific cases, the process usually looks like this:
- You build a Smeltery.
- You find a fuel hotter than lava (often Blazing Blood, which you get by melting Blaze Mobs in the Smeltery).
- You toss the diamond in.
- You pour it into a Gem Cast, not a Tool Part Cast.
But if you are playing a standard pack, trying to how to melt diamonds Tinkers Construct is a wild goose chase. You're trying to solve a problem that doesn't have a "melting" solution.
The Real Way to Use Diamonds in Tinkers
So, if you can't melt them, how do you get that sweet diamond durability? You use the Tinker Station.
In the newer versions, diamonds act as a "Modifier." They take up a modifier slot on your tool. To do this, you place your tool in the station and put a diamond in the extra slot. This adds a massive chunk of durability and increases the mining level. It’s a one-time application. You aren't casting a "Diamond Pickaxe Head." You're making a Cobalt or Amethyst Pickaxe Head and reinforcing it with the diamond.
🔗 Read more: How to Do the Cayo Perico Heist Without Losing Your Mind (or Your Loot)
It's actually a better system. It prevents the "Diamond-is-the-only-tier" trap that vanilla Minecraft falls into.
Blazing Blood and High-Tier Melting
Let's say you are playing a pack where melting is enabled. Maybe you’re on a 1.12.2 server with specialized scripts. To melt high-tier gems, you need to understand heat values.
Lava is the baseline. It melts most ores.
Blazing Blood is the step up. To get it, you need to trap a Blaze inside your Smeltery. Once the Blaze is inside, the Smeltery will "attack" it, melting the entity into a liquid. This liquid is significantly hotter than lava. If your pack allows for melting diamonds, this is almost certainly the fuel you need.
Modern Tinkers Variations
In Tinkers' Construct 3 (MC 1.16+), the developers moved away from the "melt everything" mentality. They wanted materials to feel unique. Diamonds are now "Gems." Gems are handled at the Tinker Station using Quartz, Diamonds, and Emeralds.
If you're looking for that blue aesthetic for your tool, you shouldn't be looking at diamonds. You should be looking at Cobalt. Cobalt is found in the Nether. It’s blue. It melts. It pours. It's the "Diamond tier" equivalent for Tinkers' tool heads.
Troubleshooting Your Smeltery
If you’ve confirmed your modpack does allow melting diamonds (check JEI/REI by clicking on the diamond and looking for the "Smeltery" tab) and it’s still not working, check these three things:
- Internal Tank Capacity: A diamond usually takes up 144mb or 666mb of space. Ensure your Smeltery isn't full of 10 units of leftover "Molten Glass" or something.
- Fuel Level: If your tank is empty, nothing happens. Simple, but it happens to the best of us.
- The Controller: Is the Smeltery Controller lit up? If a creeper blew up a corner of the structure, it’s no longer a "valid" multiblock.
Actionable Next Steps for Your Build
Stop staring at the Smeltery GUI. Open your Tinker Station (the upgraded version of the Tool Station). Place your pickaxe, sword, or shovel in the middle. Place a single diamond in one of the side slots.
If it shows a stat boost on the right, that’s your answer. You don't melt the diamond; you bond it.
If you absolutely must have liquid gems for a specific recipe (like making a Queen's Slime or something similar in a specific modpack), check your fuel. Swap that bucket of lava for a bucket of Blazing Blood. To get it, lure a Blaze into the Smeltery or use a mechanical pipe to pump it in from a mob crusher setup.
The complexity of Tinkers is what makes it great. Don't let the "melting" mindset limit your gear. Most of the best tools in the current meta involve mixing Alloys like Hepatizon or Manyullyn, rather than just trying to force-melt vanilla gems. Go check JEI for "Molten" liquids—if it's not there, it's not meltable. Focus on your modifiers instead. Apply that diamond manually and get back to mining.