Well I did email LOGR quite some time ago for a quote on a three stone pink gold ring without diamonds to fit very specific size stones. Never heard back from them. I think if it''s not close to something in their inventory, then they probably can''t do it. I also emailed them about specific rings in their inventory and asked to customize them for much different size heads, I did not get a lot of options. For example, there was one ring I wanted for a 11x6 rectangular stone, and they couldn''t customize any of their rectangular settings except for one that I didn''t like. It was a setting without a fancy gallery, so I think it would be a ring that would be easy to reuse the mold on by cutting it and making it bigger. I suspect, but don''t know, if they will make a brand new mold and bring your own design to life. It has to be one in their inventory.
Also be careful about customizing one in their inventory too much, I had that done, and the head was a bit asymmetrical and the workmanship was lacking. Others have mentioned the same thing. I think when they do customize their own settings, they do it very quickly and easily, without much attention to care. Therefore, from now on, I always try to get a more calibrated size stone.
Hope that helps.