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"jewelry manufacturing, the art and science book"/Black Gold

In re-examining the Romanoff book I find that there are lots of good
bits, like alloy compoisitions, one a recipe for black
gold, which I know has been asked about here before.

from page 7: “The lustrous black appearance is produced using cobalt
oxide which is said to withstand opoerations such as grinding and
polishing. The presence of cobalt in the alloy imparts a superior
mechanical strength and hardness. As an example, a gold alloy
containing 3% silver, 12% copper and 5% cobalt was rolled and
heatreated in air at 800oC for one hour. this resulted in a black
surface layer, which after polishhing had a black luster”.

My resistance to Brain Press selling the book has to do with its
organization, unsophisticated presentation and for many people, the
strong large scale manufacturing focus. I’ll have a read of mine


Charles Lewton-Brain
Box 1624, Ste M, Calgary, Alberta, T2P 2L7, Canada