The Canadian Securities Administration monitors public companies in Canada. They are keeping an eye on gender diversity and report once a year. The reports’ full title is: Report on Fifth Staff Review of Disclosure Regarding Women on Board and in Executive Officer Positions. The report only talks about gender diversity. There is obviously more types of diversity than gender.
An organization should also consider including representation of persons with disabilities, visible minorities and indigenous peoples. A best practice is to consider the profile of the stakeholders of the organization and attempt to mirror this diversity on the board. If your stakeholders are mostly younger people then your board should include younger people. If half of your stakeholders are female then you need to have females on the board. We also talk about skills diversity and geographic diversity.
A board makes the best decisions when it has all the facts and points of view. A prudent board will attempt to have all the types of people and skills represented on the board.