Moonstone is a semi-precious stone which is usually shimmering milky white in color, sometimes with showing a pronounced line or point of light in its depths called a schiller. Powdered moonstone was used in the Draught of Peace.
- Harry had to write an essay (12 inches of parchment) for Snape about the uses of moonstone in potion making (OP13).
- Bill Weasley's Aunt Muriel loaned her goblin-made tiara to Fleur for the wedding, and it was decorated with moonstones and diamonds (DH25).
Ingredient (powdered) in the Draught of Peace
In 2007, J.K. Rowling produced seven hand-written copies of the book Tales of Beedle the Bard that she gave as gifts to friends and publishers. The books had ornate covers decorate with silver and moonstones. One was given to The Children's Voice campaign charity to be auctioned off at Southeby's. It was bought by the U.S. Amazon company for £1,950,000 and put on display around the country. source: Amazon
Moonstone is found in a variety of colors. Its supposed magical effects include helping a person gain emotional balance. Since Harry spent much of book five emotionally unbalanced, it is perhaps fitting that he was forced to write an essay on the stone's use in Potions-making.
From the Web
Moonstone Lore & Legend from gemselect.com