information:highlighting, structural:summarization, structural:scholar_edition, information:extraction
Mistake of fact

An erroneous opinion as to the value of the thing which forms the subject matter of the agreement is not to be deemed a mistake as to a matter of fact. For example, a woman finds a stone and sells it as a topaz. It was a raw uncut diamond worth hundreds of times the selling price. The contract is not voidable. There was no mistake because neither party knew what the stone was. Conversely, in a case where a person sells a cow for $80 because they think it is infertile and the cow turns out to be pregnant and worth $1000, the contract would be void.