Diamond Mining Cells can occasionally be obtained from "Boss" Creatures called Things that spawn in darkness on corrupted blocks like found on the Corruption layer; either when killing them or harvesting from them when they are your Pets.
Diamond Mining Cells can also be crafted in your Crafting Menu (default key "Q"), but only after the crafting recipe for the Diamond Mining Cell has been unlocked by taking or crafting an Iron Mining Cell (like by finding one in a Diamond Treasure Chest that spawns on Lava layer blocks in the dark).
To craft one Diamond Mining Cell, you'll need:
- 4 Diamond (bars) made in a Forge from Diamond Ore that can be extracted from Nodes on the Lava layer underground or made from Coal Nodes
- 2 Iron Slabs made in a Processor from Iron Bars. Iron Ore can be extracted from Nodes on the Stalactite layer or can be found in Iron Treasure Chests or Diamond Treasure Chests
- 4 (blocks of) Tourmaline mined from the Stalactite layer, which requires at least a Stone Mining Cell; or obtained by killing or pet-harvesting Warmworms spawning on blocks of the Stalactite layer and Lava layer
- 5 (blocks of) Hardened Lava mined from the Lava layer, which requires at least an Iron Mining Cell
- 8 (blocks of) Ice, found on frozen Oceans under a thin layer of Snow, in frozen rivers or waterfalls in Taiga-biomes or Canyons, more rarely on Mountains or Frozen Deserts, or can be "produced" either with Freeze Bombs thrown against liquids like Water or made from liquids like Water when placing it on the ground of very cold Biomes
Taking/crafting a Diamond Mining Cell is one of the requirements to unlock the crafting recipes for Lumite Mining Cells, Fire Bombs, Purification Bombs, Fans, Corruption Resistance Potions, Healing Beacons and Advanced Excavators (since September 2016).
You will need Diamond Mining Cells to pull Corrupted Blocks like from the Corruption layer (or made with Corrupt Bombs thrown at corruptable blocks). With Diamond Mining Cells you can also pull Water, Tar, Bog Water and Mineral Water, but not liquid Lava nor Corrupted Water.
Durability: as of 2016 one Diamond Mining Cell can pull 400 blocks from the Corruption layer, Bog Water and/or Mineral Water before it will fall apart completely, or 800 blocks from the Lava layer and/or Stalactite layer, but infinite amounts of "weaker" blocks (Fossil layer, Stone, Dirt, organic matter like Wood etc.).