I don't think we have such a saying as good envy, but I think it can help be helpful to acknowledge when we are feeling envy. In fact it can be made into a compliment when we want to let someone know that we are impressed by what they can do that we can't yet do ourselves. That way we acknowledge it ourselves and turn it from something that could be very negative into something positive. I've sometimes had good advice with how to work to improve on something I admire in someone when I've expressed that envy. This way I've not only prevented myself from becoming bitter towards them, I've gained support and guidance.