Moonstone Gemstones is the most well known variety of orthoclase feldspar. Moonstone is fairly soft and sensitive to pressure.Blue Moonstones in fine qualities are becoming increasingly short in supply and push up the prices accordingly.Classically moonstones are always cut as cabochons.This gemstone was extremely popular in the times of "Art Nouveau", more than100 years ago. It used to decorate a striking amount of pieces of jewelry created by the famous French master-goldsmith René Lalique and his contemporaries. These pieces are usually only found in a museum or in safeguarded collections