Ugh, eternity bands. In my personal experience, eternity bands are ALWAYS asked for and NEVER purchased (and the one case in my life when one prong-set one was, the prongs underneath soon were destroyed and the diamonds started popping out). I am NOT a fan of eternity bands. Show them an anniversary band out of the case and tell them that it will look exactly like it, but with diamonds all the way around. I'm not big on throwing several hundred dollars on base metal and CZ faux rings...the reason why customers are in a physical store in the first place is to see the real thing. A simple tag to your normal wedding/anniversary band presentation ("in fact, our skilled jewelers have even created rings like this where the diamonds encircle the entire finger") will assure customers that you can make/order them. I personally would rather convince a customer to spend their money on a better quality or larger ctw normal band and not worry about the headaches of special ordering/custom, sizing issues, diamonds falling out, etc. etc. But that's just me. :)