Certificate of Origin (CoO) comes from the Chamber of Commerce; (or other valid authority) of the country of origin certifying the origin of the goods; any parts thereof and any component which is a part of the goods whether altered or processed in the preparation of the final goods. It does not certify the origin of the material used in the preparation; that is not part of the final product; for example, fuel comes for powering the machinery or the labor actually preparing/producing the goods.
For a product to “originate” from a specific country; all components as part of the final product must originate from that country. And all parts must go through preparation/production in that country. Otherwise, the CoO will state that the product has been “assembled” only but not produced in that country. Or the CoO will state that for instance sugar has been refined in the Philippines based on the product from China.