Cool Gold

Testing Blue and Purple Gold Alloys

By Linus Drogs

Editor’s Note: In this online exclusive, Linus Drogs of Au Enterprises in Berkley, Michigan, presents the results of his experiments casting blue and purple gold. A related study, aimed at improving the crack resistance of 14k blue and 18k purple gold alloys, was summarized in the March 2010 MJSA Journal. (The results were first presented at the Santa Fe Symposium on Jewelry Manufacturing Technology.)

Blue gold. I began by casting the 14k blue gold into a simple band. Using standard casting equipment (I use a Neutec machine with argon cover gas) and a flask temperature of 600°F (316°C), we cast the band at 1,050°F (566°F). The material cast successfully with no noticeable surface irregularities. As you can see on the casting, the oxides that form on the surface have a distinctive blue hue; however, when you polish off the oxides, the color of the actual metal is closer to a silvery gray with a bluish hue. Anyone in the industry who knows metal colors would say it looks blue, but a consumer would think it’s actually more of a gray color. Giving the casting a sandblasted finish as opposed to a high polish enhances the blue tone.