What precisely is the proper level of inequality? i.e. what is the Gini coefficient of an equal society? I've never seen it calculated. (It's not 1.0 since t

What precisely is the proper level of inequality? i.e. what is the Gini coefficient of an equal society? I've never seen it calculated. (It's not 1.0 since there are age effects, plus it's expected that immigrants will be poorer than well-established people, etc.)