Soldering is a process for using still another metal or alloy which has a lower melting point but which is compatible with the metals to be fastened. A “hard” solder of diamond wedding bands is an alloy selected to make a very strong bond and which has a higher melting point. Such solders are used for silver, gold, and platinum work. “Soft” solders are low-melting-point tin-lead alloys. These are generally used by electricians and plumbers. The joint to be soldered, in any case wedding bands, is cleaned thoroughly. A “flux,” an easily melted substance such as borax, is applied. It melts and covers the joint, preventing oxidation as the required high heat is applied. An appropriate amount of solder is added to the joint and melted in to make a permanent union. There are numerous special methods used to solder diverse kinds of objects and there are numerous solders to go with them. However, basically the process is this simple. Platinum, unlike gold and silver, has a very high melting point (3224°F.) and does not oxidize at high temperatures, so joints can actually be welded—melted together—rather than soldered. Some gold diamond jewelry metal alloys contain a percentage of copper. After exposure to the heat of soldering, objects made of these alloys will blacken because of the formation of copper oxide. This “fire scale,” as it is called, can be removed quickly by “pickling”—bathing in an acid solution which dissolves the black copper oxide and any excess, now-hardened flux.