DuracellEnergizer said:
The Jewel of the Nile (1985)
It certainly is funny what tricks the mind can play on you. When I watched this movie back as a kid, I distinctly remember there being a literal jewel in it -- a large, fist-sized ruby. Yet watching it again last night, there wasn't a literal fist-sized jewel -- ruby or otherwise -- in it at all. The closest the film ever gets to one is the jewel-encrusted dagger the Sufis give to DeVito's character at the end.
You're probably confusing it with the first film in the series, Romancing the Stone, which did have a large jewel:
