When it comes to doing anything in jewelry the cleaner the gas burns
(translated less carbonizing of surfaces) the better. Use propane or
natural gas with a large “rosebud” tip. Propane burns very cleanly and is
hotter than natural gas. The draw back is that it is more potentially
dangerous to use because it is a compressed gas (bottled) and for some
delicate soldering operations it could turn your beautiful filigree
pendant into a ball of metal unless you are very careful/experienced using
it.
Good luck, Mike Campbell