(a) A valuation fraudulent in fact entitles a marine insurer to rescind the contract.
(b) When the subject matter has been hypothecated by bottomry or respondentia, before its insurance and without the knowledge of the person actually procuring the insurance, such person may show the real value.
(c) Otherwise a valuation in a policy of marine insurance is conclusive between the parties in the adjustment of either a partial or total loss if the insured has some interest at risk and there is no fraud on his part.