Professional Jeweler Archive: Sterling Silver Alloy with Platinum

March 2005

Bench | Welding Technologies

Sterling Silver Alloy with Platinum

New alloy allows new creative opportunities

By Mark B. Mann

Marc “Doc” Robinson, technical director and chief metallurgist for ABI Precious Metals, Carson, CA, invented and developed a line of sterling silver alloys containing platinum about a year ago. Manufacturers, designers and manufacturing retailers have been using them to create exclusive product lines. The tarnish-resistant sterling alloy containing platinum comes in three compositions. The chart at right describes the details.

Robinson invented the alloys to allow for higher-price-point designer lines and to offer a premium sterling alloy for fine gemstones and diamonds. The following are also benefits:

  • Increased hardness.
  • Greater weight density.
  • Excellent casting performance.
  • Rich, deep sheen and excellent surface finish.
  • Tarnish resistance that requires no plating.
For the pulse-arc welding project featured on pages 73-75, I cast two buttons of bracelet links – one with links made of sterling containing platinum (right) and the other with common sterling silver (left). These images are of the buttons after investment is removed. As shown, the sterling with platinum cast clean and white while the common sterling is dark.
After pickling, there’s little difference in appearance.
The link on the left is a sample of common sterling. The link on the right is sterling with platinum. Both were prefinished and magnetic-pin finished using the same procedure.
Both alloys took about the same time to prefinish and finish because no torch or soldering was required. Had a torch been used, the sterling with platinum would have been quicker and easier to finish because it resists firescale and oxidation.

Charles Bennett of ABI Precious Metals has produced hard and medium solder that matches the hardness and brightness of sterling with platinum alloys for use in sizing and fabrication. He advises not to use common sterling silver solders because a line will be visible in the finished product. When easy solder is needed – such as for attaching a bezel or other components to a sterling with platinum piece – he advises using 10k white plumb easy-flow solder. He’s conducting further testing on other components of sterling with platinum and also developing new gold alloys with platinum.

For information on sterling with platinum alloys and other products, contact ABI Precious Metals at (310) 769-0600,

Photographs by Mark B. Mann
Visual Communications, Inc. © 2005

Copyright © 2005 by Bond Communications