On installation be sure to install QuickTime 2.0.3 (this seems to coexist happily with later versions of QuickTime on my machine, including 2.1.2 and 6). After installation, select the executable JLAUNCH.EXE in the JEWELS directory, right mouse click, select Properties, then the Compatibility tab. Set Windows 95 compatibility, and click 640x480 resolution. The game now runs correctly.