These rainbow moonstones are just stunning to behold.  Not only are they at a large size which is difficult to come by in such quality, they are also beautifully translucent with intense blue fire.
 
Measuring at a bold size of 25.5mm x 19mm I've pair these intense blue fire gems with natural blue sapphires bezel set in 18k white gold beneath ear wires of 14k white gold.
 
Overall length is 1.75".