"... Silver and gold jewelry is assembled using "hard" solders and a torch - usually oxy/propane or oxy/acetylene. "Hard" solders are alloys of silver or gold that melt at slightly lower temperatures than Sterling silver or the various karat alloys of gold. The confusion arises because the lowest temperature "hard" solder is sometimes called "soft" solder. A better term might be "easy" for the lowest temperature hard solder. "Hard" solder typically comes in "easy," "medium" and "hard" grades. A complex piece would be started with hard solder, the next elements would be applied using "medium" solder an the last parts tacked on with "easy" solder. This way the solder holding the first elements would not flow or move when the rest of the parts are assembled. ..." ---
http://www.rings-things.com/solder.htm
http://www.solder-it.com/solderpaste.asp
Silver Bearing Solder-It (SP-7)
It will solder most ferrous and non-ferrous metals including copper, brass, bronze nickel, platinum, (some) chrome, monel, galvanized, (some)stainless, gold, silver, coated steel, cast iron, black steel, steel.
The Silver Solder Paste above comes in a 0.5oz syringe. It will solder small jobs with the heat from a match or lighter even. It is extremely thermal conductive because of its silver content too.
My wife's cousin works in a jewelry store repairing jewelry all day. He keeps a low flame and hand waves the parts to braze them together. He had to go to school for two years just to learn how to wave his hand.
Stev