Thank you for the reply. I wish to seek further clarification though.
Text books on Indian Contract Act do make a mention that in case of innocent misrepresentation, one party can claim that the injured party had the means to discover the truth with ordinary diligence, and therefore the contract remains valid.
However, that is not the case with fraud. In this case, the party cannot claim that the injured party had the means to discover the truth with ordinary diligence. Hence the contract remains voidable because of the existence of fraud. It is also mentioned that where there is active concealment, the contract is voidable even though the aggrieved party had the means of discovering the truth with ordinary diligence.
However, exception to Sec 19 states that contract is not necessarily voidable if the aggrieved party could discover the truth by ordinary diligence. Hence my doubt.