Alexandrite

Alexandrite was once considered a fancy stone, but by the Year of Wild Magic, 1372 DR, it had surged in price to that of a precious stone, and maintained its value through the Spellplague and beyond.

Description
This transparent gem was a form of chrysoberyl that was green in hue under natural light, but appeared reddish when viewed under non-natural lights such as arcane light spells. It was usually facet cut and used for jewelry such as earrings or pendants. In the mid–14 century DR, one of these stones had a base value of 100 gp, but since that time a typical specimen had a base value of 500 gp.

Powers
Alexandrites were used as a magic focus for items that provided good luck, favorable reactions, protection, or other good omens. Examples included luckstones and the cursed lodestone.

Trivia
Alexandrite gems were considered sacred to Gaerdal Ironhand. It was appropriate to consecrate or sacrifice alexandrite to him, or a follower might find one as a boon or an omen.

According to a well-known nursery rhyme, some sages said that alexandrite came from the body of the oldest son of Sylvanus.