Moonstone is a sodium potassium aluminum silicate of the feldspar group that displays a pearly and opalescent schiller. It is also known as Hecatolite and is the most valuable stone of the feldspar group. Moonstone can occasionally be confused with Opalite, but Opalite is a man-made stone made to resemble Opal. Moonstone has been used in jewelry for millennia, including ancient civilizations. In more recent history, moonstone became the hallmark of the Art Nouveau period. Moonstone has been a popular gemstone for jewelry throughout history and still is today. It was also thought to protect sailors at sea and travelers on water. Like the moon, the stone is reflective and reminds you that everything is part of a cycle of change.