If it is tinged by sadness or pity then it isn't pure. Sympathetic joy is the wish that all beings continue to enjoy the pleasures they have attained. This is a somwhat neglected contemplation and many find it difficult to practise. It overcomes the petty-mindedness of jealousy and envy. The near enemy is sensual pleasure and the far enemy is aversion and boredom.
Equanimity is the highest and most refined of the divine abidings.
It purifies the subtle attachments that the others may still harbour. Equanimity has an important place in Buddhist mental development. In the jhana path it is the mark of fourth jhana, that which transcends rapture and bliss. In the insight path, the stage of equanimity of formations is the jumping off place for enlightenment. The mind which picks and chooses is still mired in the world of grasping, and is bound to birth and death.