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Quality Assurance Benchmarks highlight workmanship of semi-finished and finished jewellery. Learn how to remove oxidation from an assembled ring made from platinum cobalt components with these helpful illustrations and instructional video.

Close-up view illustration of a four-prong platinum setting.

These benchmarks relate to the removal of oxidation. This oxidation occurred during the soldering process when assembling the platinum cobalt setting and mounting.

After the removal of oxidation, there should be no discoloured or darkened areas.

There are no tool marks or other evidence of mechanical removal.

The finish where the oxidation was removed is even and smooth.

Potential Problems and Engineering Features

Oxidation that occurs on platinum cobalt is dark, spotty, and covers certain areas on the piece, depending on the soldering situation. For best results when removing oxidation, firecoat the piece, mildly heat and then pickle.

Platinum cobalt solitaire with dark, spotty oxidation visible on the shank and setting of the ring

Here, the setting was soldered into the ring mounting and the resulting oxidation is random.

Mechanical removal of oxidation is another option, but it is time consuming, reduces the metal's dimensions, and would be difficult given the limited accessibility to the areas where it would be concentrated.

How-to Video

Removing Platinum Cobalt Oxidation

play

Removal of Firecoat Prior to Soldering

The following problems can occur during normal wear if the piece is firecoated and the firecoat is not removed before soldering.

Do not firecoat platinum cobalt jewellery prior to soldering unless gemstones are set in the jewellery. Firecoating will help to protect the gemstones.

If the piece contains gemstones, apply firecoat and then clean the firecoat from the joint prior to soldering.

In this example, the ring contains diamonds. Here the technician is wiping away the firecoat with a cotton swab and water. The diamonds are protected by firecoat and a wet paper towel.

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