Diamond eternity ring

A customer has asked me to make an eternity ring for her in 18ct white gold using some diamonds which she has bought abroad. The stones are about 20pts each and there are 14 of them. A quick calculation shows that this wont be quite enough to go all the way around as she would like them in a channel setting and therefore close together. An investigation shows that a casting for this job is unavailable so time to make something from scratch!