Actually they have worked on the alloys for purple gold and some of them are not so brittle. In fact one former student of Alan's has the patent on severl variations that some of which are malable to a degree. As a metalsmith first then a jeweler, working with these alloys is not beyond me. I just want to be more sure of what alloys are best before investing in the gold to cast all of this. Oh and you can first cast the purple gold then recast another color of gold on top or next to it. I've done that many times so it sounds more and more doable. Darn now I've talked myself into another project.
http://www.utilisegold.com/jewellery...ecial_colours/ http://www.professionaljeweler.com/a...8/0498pm1.html
The last link has a great photo of a overlay of blue gold