Eric, Purple gold is an alloy of 78.5% pure gold and 21.5% aluminum.
Aluminum oxidizes rapidly as it melts, so this must be done in an
oxygen-free atmosphere. If the metal oxidizes, it turns into a black
sponge. This alloy is not easy to make, and you will probably commit
a couple of ounces of gold to your learning experience.
The alloy is also very brittle. If you hit it, it will shatter into
dust. It will not be possible to draw it into wire or roll it into
sheet. I don't know how you can make granules, unless by accident.
Since this alloy does not contain copper, probably the only way to
attach it to the surface of yellow gold would be to solder it. If
you did manage to get purple gold granules to attach to a yellow
gold wedding ring, they would certainly disappear the first time you
bumped it against anything.
A wedding band tends to get worn a lot, for a long period of time,
so I would consider the durability of the design as an important
element. Granulation, either 22k or 18k, is by nature a soft alloy
and the tiny grains are easily crushed and broken off. They also
An easier way to add purple color to a ring would be to use a purple
stone. Amethyst is easy to cut into tiny cabs and inlay into the
surface. You can also use lavender jade or sugalite. You could make
granules by crushing rough into sand and tumble polishing it. I've
never seen anyone do this, so you may be the first. I would suggest
that you set each tiny stone as deeply as possible, or they will
break off or wear smooth.
Let me know how this works out.