Let's have a chat about purple shadow... not purple haze, not purple rain... purple shadow, otherwise known as fire scale: the bane of every silversmith's existence.
Sterling silver is an alloy of copper and fine silver in the proportion of 925 parts silver, 75 parts copper. But don't be fooled by that tiny bit of copper, it is a trouble maker. Copper is the reason that sterling silver tarnishes. Fine silver (999 parts silver) is much more tarnish resistant.
As you work with the silver (file it, hammer it, sand it, form it) the alloy is getting moved around, compressed... and this compression brings the copper to the surface of the silver. As the alloy undergoes this compression, "islands" of raised copper start forming and create portions in the surface of the metal that tarnish faster than the surrounding metal... and these "islands" manifest as purple shadows on the surface of the silver.
There are two ways to get rid of fire scale. 1. continue filing/sanding until the island of copper is gone. 2. go through several rounds of heat/pickle (heating the metal to bring out the oxidation then throwing the hot metal into acid so that the oxidation is eaten away), a process known as "raising the fine silver." I prefer method 2 because I find method 1 risky... I never know how deep the fire scale goes, and I could very well file through the whole piece before the fire scale is gone.
It's the mark of a well made silver piece to have no fire scale... it's a time consuming process to get rid of purple shadow and it is definitely a labor of love. So, the shadow definitely knows how much time was put into the jewelry you wear.
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