In conversation, I just said:
L'argent n'a de sens que correctement utilisé.
In hindsight, though, I'm not sure if this structure is grammatical. A conditional clause like "correctement utilisé" without "si/quand" is usually used, as in:
(S'il / Quand il est) Correctement utilisé, l'argent peut vous ouvrir bien des portes.
Can the restrictive "ne ... que ..." qualify this conditional clause without "si/quand"? I think I'm so used to the structure "ne ... que si/quand ..." that the omission of "si/quand" after "que" subconsciously struck me as odd.
Even if it is grammatical, I wonder if it is seen as rather formal in register?