California Code, Insurance Code - INS § 381.2

When a policy includes coverage for loss or damage to a specific item of personal property of the insured, which item is separately listed and described and on which item a separate amount of insurance is placed, the insurer shall compute any total loss of such item of personal property as being the amount of insurance placed on it.  In the adjustment of a partial loss or damage to such item of covered property, the separately listed amount of insurance applying to the specific item shall be used as the value of the item prior to its partial loss or damage.  If a different method is to be used in the computation of loss, the policy, and any application therefor, shall set forth, in type of prominent size, the actual method of such loss computation used by the insurer.

The provisions of this subdivision shall not apply to any property used for a business purpose or to any motor vehicle.

If there are two or more policies insuring the same property against the loss, the loss shall be prorated among the policies.