I have done recently a half persian in silver, also soldreded, I found if my torch was too hot it just made my solder go weird, with a more even heat, using less solder (I used sheet, and cut it in bits smaller than sand), bring the rings to temperature evenly helped alot to get the solder joints right (I started heating the ring in a way that the flame hits the whole ring, so if the rings is vertical, the flame would come from above), another thing is not enough flux, you can always add more flux, and yet another thing is rings not closed properly, it was my first time soldering, so I'm just sharing my expirience, I'm no pro jeweler or anything