|When you play this, count your deck and discard pile. Worthper 5 cards total between them (round down).|
Philosopher's Stone is a Treasure card from Alchemy. It grows in value as the number of cards in your deck and discard increases, favoring huge, bulky decks. It does not count cards in your hand or in play and so favors a thick-deck, low-drawing strategy, differing from most other Alchemy cards.
 Official FAQ
- When you play this, count the number of cards in your deck and discard pile combined, divide by 5, and round down. That is how many this produces for you.
- Once played, the amount of you got does not change even if the number of cards changes later in the turn.
- Make sure not to change the order of your deck when counting it; the order of your discard pile does not matter.
- You will get to look through your discard pile as you count it.
- You only count your deck and discard pile, not your hand or cards in play or set aside cards.
 Other Rules clarifications
- Since the release of Prosperity, it is actually possible to play multiple copies of Philosopher's Stone that give different amounts of , in spite of the official FAQ. For example, if you have 20 cards in your deck and play this, it produces . Then, you could play a Venture, which could reveal and play another copy of this. When you play the second copy, you would only have 19 cards in your deck, so it would only produce .
 Strategy Article
There isn't a strategy article for Philosopher's Stone.
It's typically a pretty weak card, with a few exceptions:
- The Combo: Philosopher's Stone and Herbalist
- Familiar lends itself to bloated decks which already have a Potion in them.
- Combo: Philosopher's Stone and Herbalist: Herbalist gives you the +Buy needed to bloat your deck to increase the value of your Philosopher's Stones (as well as to effectively spend all the money produced by high-value Philosopher's Stones). It also allows you to reuse the same Potion to buy Philosopher's Stones for multiple turns, or to reuse the same Philosopher's Stone to buy Victory cards.
- Sifters like Cellar and Warehouse let you find your Philosopher's Stones and increase their value by discarding. Storeroom is especially powerful with its +Buy for more coppers and second discard for coin
- Goons: using up all your extra buys will be rewarded both by increasing the value of your Philosopher's Stones and by Goons giving you victory tokens. (However, this is only viable when there isn't an available engine strategy that can efficiently play multiple Goons per turn; Philosopher's Stone tends to be weak in a deck like that.)
- Scavenger: Playing Scavenger can allow you to consistently top-deck a Philosopher's Stone, which can often be worth enough to virtually guarantee getting a province the following turn.
- Hero can gain Philosopher's Stones without having to get a Potion first.
- Philosopher's Stone works poorly with engines that involve drawing and playing large numbers of cards on a turn, since cards in hand and in the play area don't contribute to Philosopher's Stone's value. (Ironically, this means Philosopher's Stone works poorly with most Alchemy cards other than Herbalist.)
 English versions
|When you play this, count your deck and discard pile. Worthper 5 cards total between them (rounded down).||Alchemy 1st Edition||May 2010|
|When you play this, count your deck and discard pile. Worthper 5 cards total between them (round down).||Alchemy 2nd Edition||December 2018|
 Other language versions
Philosopher's Stone is the only-costing card that gives + .
 Secret Historyper 4 cards left in your deck." It was in the original Alchemy, but I considered it for the main set at one point (when Gardens moved there). Eventually I brought it back as a treasure. First it counted cards left in your deck. Some people don't like how huge the variance is on that though. I can make a card here and there like that, but not too many. I dropped it, then later brought it back with "put your deck into your discard pile" (and then it counted your discard pile). That still had high variance, a different way; you might draw it immediately after shuffling, which was a lot better than not drawing it immediately. Finally I changed it to how it is now. The random element is completely gone; it still isn't consistent, due to card-drawing and such, but that's your own problem.