is there anyone in the Northeast who's consistently casting either
Stuller's "X1" or W.R. Cobb's "Precise White" and can cast a piece
for me in 18K?
Au Enterprises in Berkely, Michigan (800-637-2278) casts X1 in 14K
and 18K. I've been using their services for 10+ years for platinum
casting. They are a superb commercial casting house. You can expect
the casting to be clean, smooth, and porosity-free. And they have a
2-3 day turnaround.