Stardew Valley, while primarily a farming simulation, offers players a wealth of activities beyond just tending to crops and animals. A key aspect of the game involves turning your small farm into a profitable enterprise, and one lucrative venture is mining for gemstones. These gems are not only beautiful and valuable but also essential for crafting and make thoughtful gifts for the townsfolk.
However, the relentless search for rare gemstones in the mines can become tedious. This is where the 
Crystalarium proves invaluable. This ingenious device allows players to duplicate a single gemstone or mineral, producing dozens or even hundreds more over time. Here's a detailed guide on how to harness the power of the Crystalarium in Stardew Valley.
Updated January 6, 2025, by Demaris Oxman: The 1.6 update introduced significant changes to Stardew Valley, including subtle adjustments to high-level items like the Crystalarium. This guide has been updated to reflect these changes, ensuring players have the latest information on how to utilize the Crystalarium effectively.
Obtaining A Crystalarium
To unlock the Crystalarium crafting recipe, players need to elevate their mining skill to Level 9. Crafting one requires the following materials:
- 99
Stone: Easily obtainable by breaking rocks on the farm or in the Mines with a Pickaxe. - 5
Gold Bar: Crafted from Gold Ore, which can be mined at Level 80 and below in the Mines, using a Furnace and 1 Coal to smelt 5 Gold Ore into a Gold Bar. - 2
Iridium Bar: Iridium can be found in Skull Cavern or obtained daily from the Statue of Perfection. Use the same smelting process as with Gold Bars. - 1
Battery Pack: Collected by placing Lightning Rods outside during thunderstorms. They charge and produce Battery Packs when struck by lightning.
Even without the recipe or the rare materials, players can still acquire a Crystalarium through other means:
- Community Center Bundle: Completing the 25,000g Bundle in the Vault section of the Community Center rewards players with a Crystalarium. Simply donate 25,000g to unlock this.
- Museum: Donating at least 50 minerals (Gemstones or Geode Minerals) to the Museum Collection will earn players a Crystalarium from Gunther.
Using The Crystalarium
After crafting, players can place their Crystalarium anywhere on their farm or elsewhere, such as the Quarry, which is a favored spot for setting up a crystal farm.
The Crystalarium can replicate any mineral or gemstone inserted into it, with the exception of Prismatic Shards. Among the options, 
Quartz has the shortest replication time, but due to its low value and abundance in the mines, it's not the most profitable choice. Conversely, 
Diamonds take the longest time to replicate, at 5 days, but their high value makes them the most lucrative gem to use.
To relocate a Crystalarium, players should strike it with an ax or pickaxe, which will return it to their inventory along with any gem currently being replicated. To switch the gem inside, simply insert a new gem while interacting with the machine. For instance, if a Crystalarium is producing Rubies and you want to switch to Diamonds, just interact with the machine while holding a Diamond; the Ruby will be ejected, and the Diamond will start the replication process.
By strategically using the Crystalarium, players can significantly increase their profits and become beloved in Pelican Town for their generous gifts of precious gems.
