Cooksons only supply 18ct red gold wire fully annealed. I need some 0.8mm fully hard. I can order larger diameter and draw down to the size I want, thereby hardening it in the process. Can anyone suggest what diameter I should start with in order to finish with 0.8mm fully hardened? Or is there another way to harden it effectively? Looking at the table of Au-Ag-Cu gold alloys in Grimwade (Introduction to Precious Metals, p.105) it appears that 18ct red can be aged at 280C for an hour for maximum hardness, similar to the way I do Argentium. If I can shape first, then harden by heating after, that would be ideal. Has anyone tried this? Any advice, potential problems, etc?

Alan