What should I know before sizing a Platinum/Iridium ring?

Safety first! Solder platinum only if #5 or #6 welding safety glasses protect your eyes. Permanent damage to eyesight may occur as a result of UV exposure. Sunglasses do not provide adequate protection.

Begin with a saw, files, and other tools reserved only for working platinum. Contamination may occur from tools used to work silver and gold. This also holds true with finishing buffs and compounds.

Fit seams very closely. Attempting to fill large gaps will result in pitting and visible seams.

Clean and pickle all components thoroughly.

Use only a tungsten carbide solder pick, and tungsten carbide or ceramic tipped tweezers. Steel and titanium soldering tools will result in contamination. Use only ceramic or refractory supports; never use charcoal or other carbon fixtures. Carbon is probably the most frequent cause of contamination when soldering platinum.

Either Platinum/Iridium or Platinum/Cobalt stock may be used when sizing up, however it is best to use stock of the same alloy as the ring. Fusing or welding, due to differences in melting temperatures, cannot join Platinum/Cobalt and Platinum/Iridium. However, soldering may join these two alloys and 1700°C solder is the best choice whenever this is necessary. All platinum solders below 1700°C will result in a dark, visible seam line.

Place the solder chip in seam, not on top of seam. Apply heat directly to the solder and seam until the solder flows.

Flux and boric acid fire coat are unnecessary, and may cause Platinum to become brittle.

Use a hydrogen torch or oxy/natural gas or oxy/propane gas torch. Acetylene, which is rich in carbon, is never recommended. A sharp, slightly oxidizing flame works best for Platinum.

All Platinum solders flow at temperatures greater than any stone - including diamond - is capable of withstanding. To avoid damage to prong set stones, orient the stones at six o'clock and the seam to be soldered at twelve o'clock; then direct the flame upward to the seam. Caution is advised when sizing heavy bands and when channel set stones are involved. When this is the case, it is better to use white gold solder and have a visible seam rather than damage a stone. Using a small brush for application, protect all stones by coating them with a boric acid fire coat.