When a new attribute is created and intended to be used as a search refinement on a storefront in Salesforce B2C Commerce, it is essential not only to create the attribute and set it up as a refinement but also to ensure that the attribute has data and is indexed. The indexing of the attribute makes it searchable within the platform's search framework, enabling the storefront to use this attribute as a filter or refinement criterion. If the attribute is not indexed, it will not be available for search refinements, thus not appearing or functioning in the site's search or filter options. This step is crucial for the functionality of filtering products based on specific criteria or attributes.