Cal. Evidence Code § 813

(a) The value of property may be shown only by the opinions of any of the following: (1) Witnesses qualified to express such opinions. (2) The owner or the spouse of the owner of the property or property interest being valued. (3) An officer, regular employee, or partner designated by a corporation, partnership, or unincorporated association that is the owner of the property or property interest being valued, if the designee is knowledgeable as to the value of the property or property interest. (b) Nothing in this section prohibits a view of the property being valued or the admission of any other admissible evidence (including but not limited to evidence as to the nature and condition of the property and, in an eminent domain proceeding, the character of the improvement proposed to be constructed by the plaintiff) for the limited purpose of enabling the court, jury, or referee to understand and weigh the testimony given under subdivision (a); and such evidence, except evidence of the character of the improvement proposed to be constructed by the plaintiff in an eminent domain proceeding, is subject to impeachment and rebuttal. (c) For the purposes of subdivision (a), “owner of the property or property interest being valued” includes, but is not limited to, the following persons: (1) A person entitled to possession of the property. (2) Either party in an action or proceeding to determine the ownership of the property between the parties if the court determines that it would not be in the interest of efficient administration of justice to determine the issue of ownership prior to the admission of the opinion of the party.