Every organisation is different; people, size, culture, industry, context all have an impact on the way Purpose and Values are developed, so proposing a standard development process that is going to work for all organisations is not possible, or desirable.
All organisations need to deliver on their promise to their clients, customers or other stakeholders. To do so they need to deliver on their promise to their people. Values, and their associated behaviours, are part of that promise.
Only when purpose is really clarified, can attention can be truly focused. Purpose is not a by-line or a marketing motto. It is the fundamental capture and sincere articulation of the soul of the business, but when it is found, it transforms everything.