Philosopher's stone

The Philosopher's Stone is a lifetime reward in The Sims 3: Supernatural. This object allows a Sim to turn portable items into gold ingots as well as allowing the household to summon playable ghosts. However, there is a chance that the Sim will fail in the attempt to turn the object into gold, or worse, die by turning into gold. Should a Sim be killed by such accident, the gold statue may be sold for an hefty sum, and can be named by the Sim killed in the action, should the Sim be revived.

It looks quite inefficient, as gold ingots produced by an individual action is around §150. This is compounded by the risk involved in the transmutation (although one could exploit it by giving the Sim a Death Flower, or the Sim has the trait(s) of Unlucky or Loser), thought the technique relies in having the ghosts transmute gold in your Sims's lot to get an infinite income of gold statues worth of §50,000. This does have some value: things with no value such as old newspapers, potions, seeds, etc. can be turned into gold ingots. In addition, converting things like old newspapers also allows a Witch to turn gold ingots into something else with the transformation spell.

The ghost of a Sim killed by being transmuted will be gold.