Sterling Silver 925 adjustable "Daisy" ring.  Flower shapes hug up to the blue Bombay Sapphire gin bottle 10mm glass and the overall diameter is approx 20mm which makes for a generous size overall.  This setting is really stunning and one of my personal favourites.  
 
Simple to fit with a gentle but firm squeeze both from sides and top/bottom of ring while on your finger to seek a comfortable fit.  This should only need to be done a couple of times. 
Size range from:  6.5 -- 17mm - N
                            to:  10  -  20mm - U