Pure Diamonds & the Diamond Forge

The genuinely scarce mid-to-late-game currency. You don't mine Pure Diamonds. You slowly refine them from ordinary Diamonds at the Diamond Forge, then spend them on the deepest upgrades and gear in the game.

What are Pure Diamonds? #

Pure Diamonds are the bottleneck resource that unlocks the entire Diamond Mine economy. Unlike Coal, Bronze, Iron, and Diamonds (which scale into astronomical numbers), Pure Diamonds stay deliberately rare. Even a single one is meaningful early on, and a stack of them is a serious reward. That scarcity is what makes them the price tag on nearly every powerful thing down here.

You can't gather them by hand. Instead you purify your regular Diamonds one at a time at the Diamond Forge, a slow machine tucked into a cave just left of Overseer Korrin in the Diamond Mine area.

📜“The first thing you should do is look for the Diamond Forge… Purifying your diamonds will make them much more valuable, and you'll be able to purchase powerful items with them.” Overseer Korrin

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The Diamond Mine and the Diamond Forge are areas you travel to within the world, not a separate place. Reach the Diamond Mine at Time Leap Diamond Breaker (once you've reached the Stone Age).

The Diamond Forge #

The Diamond Forge is a purifier with a handful of slots. You load a slot to start purifying, wait out its timer, then claim 1 Pure Diamond. Each slot works independently, so more slots means more Pure Diamonds cooking at once.

How it works

Start a slot → it converts 1 Diamond → 1 Pure Diamond over time → claim it when the timer finishes.

Base time

5 minutes per Pure Diamond, cut by 1 minute per level of the Blazing Forge upgrade (up to 3 levels, so as low as 2 minutes).

Slots

You start with 1 slot. The Deep Crucible upgrade adds another, and a rare Forge Ember can grant one more permanent slot.

Cost per purify

A mix of Diamonds and Coal. Both ramp up the more you've ever purified: the Diamond cost climbs steeply before leveling off, while the Coal cost keeps scaling.

Instant finish

Impatient? You can spend extra Coal to finish a slot's remaining time immediately. The more time is left, the more Coal it costs.

Because the cost ramps with every purify, your early Pure Diamonds are cheap and later ones get pricey. That's intentional. The Forge is meant to be a patient, steady trickle you keep running in the background while you mine, fight, and grind other stats.

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Keep every slot busy at all times. An idle slot is a Pure Diamond you're not earning. Prioritize Deep Crucible (an extra slot) and Blazing Forge (faster purifies) early in the upgrade tree. They pay for themselves fast.

The Auto Diamond Forge #

Manually restarting slots gets tedious. Complete both quests from the Collector to permanently unlock the Auto Diamond Forge. Once active, it automatically claims each finished Pure Diamond and re-starts the slot for you (for a small extra Coal cost per cycle) as long as you're online and can afford the ingredients.

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The Auto Forge runs while you're online. When it purifies a Pure Diamond you'll get a little Auto Forge notification. If you ever run out of Diamonds or Coal, it simply pauses that slot until you can pay again.

See the Collector page for the exact quest goals, and the automation page for the rest of the game's hands-off systems.

What Pure Diamonds buy #

Every Pure Diamond you refine is fuel for the Diamond Mine's biggest power spikes. The main sinks:

Spend on	Where	What you get
Pure Diamond Upgrade Tree	Upgrades NPC (Diamond Mine)	A permanent skill tree: forge slots & speed, resource multipliers, combat and mining boosts. Nodes cost from 1 up to hundreds of Pure Diamonds each.
Diamond gear	Diamond Smith	Diamond-tier pickaxes, swords, and armor.
Artifacts	The Collector	3 random artifacts per day, priced from 1 to 25 Pure Diamonds.
Drills	Drill Mechanic (Tectonic only)	Automated mining drills that dig even while you're offline.
Signature items	Alignment traders	The Deep Breaker pickaxe (Tectonic) and the Ascension Feather (Ascension), among others.

Runes are the odd one out: the Geode Pack at the Diamond Mine costs 1 Pure Diamond per roll, so if you're chasing rare geode runes, budget for it.

Tips #

Grow your Diamond Fortune: more Diamonds mined means more raw material to feed the Forge and a cushion against the rising per-purify cost. The Crystal Bounty node (×2 Diamond Fortune per level) is the classic first buy.
Pure Diamonds never reset. Like every item and every ore, they survive a Seconds reset, a Chrono Dust reset, a Time Leap, and an Era reset. Nothing you refine is ever lost.
The upgrade tree unlocks the moment you've ever reached the Diamond Breaker Time Leap tier, so it stays open even if an Era reset lowers your current tier, since your best-ever tier only ever goes up.
Type /warp to travel to the Diamond Mine quickly, and /guide to open this wiki in your browser whenever you need a refresher.

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Treat the Forge as always-on infrastructure: unlock every slot, get the Auto Forge running, and let it stockpile Pure Diamonds while you focus on combat and the rest of your mining.