John Stott writes,
"Not all envy is tainted with selfishness, because it is not always either a grudging discontent or a sinful covetousness. At base, envy is the desire to have for oneself something possessed by another. And whether envy is good or evil depends on the nature of the something desired and on whether one has the right to its possession.
If that something we desire is in itself evil, or if it belongs to somebody else and we have no right to it, then the envy is sinful. But if the something desired is in itself good, a blessing from God, which He means to have all people enjoy, then to 'covet' it and envy those who have it is not at all unworthy."
(Source: John Stott's Commentary on Romans, p. 297.)