I don't know about everyone else, but finding fin and fashionable rings in larger sizes seems to be next to impossible! Rings are actually one of the first pieces of jewelery I made because I pretty much gave up on ever finding anything reasonable priced.
Please do not misunderstand me. I know that I can always have a ring resized to a larger size (and in fact do it frequently for my customers), but they always look like "regular" rings sized up, and not like they were designed to look right at their current size.
My rings are available custom made to a size 15. I actually use larger size stone, and create my patterns with graduated sized cutwork so my pieces never look like "little rings made bigger" and instead look balanced and harmonious.
Top right is sterling silver and amethyst. The centre stone is 10mm across and a gorgeous dark purple colour with no visible flaws. Bottom left is a hammered sterling silver band with a 5mm dark green emerald and no additional embellishments. It has a very rustic, almost viking-like look to it and never fails to get noticed. These items are no longer available in my etsy store, but can be remade to order in any size imaginable.