This is a nice blue medium teardrop rainbow moonstone set in a medium gage Sterling silver wave ring design.
This ring is a size 7 1/2 but can be sized from a 6 to a 9.
The stone used here measures 22 by 12 mm or just over 3/4 by 1/2 inch.
Shipping is free to the USA and Canada.
Rainbow Moonstone is actually more specifically a labradorite. Traditional moonstones belong to the orthoclase feldspar group while rainbow moonstone comes from the labradorite feldspar group. Another proper name for Rainbow Moonstone is “spectralite