The Legend of the Emerald Lady [SEP] series
The Legend of the Emerald Lady
The Legend of the Emerald Lady is a book in the Nancy Drew mystery series by Carolyn Keene. It was released in paperback on May 1, 2000. 
Plot summary.
In the book, Nancy solves a mystery on the Caribbean island of St. Ann when visiting Sugar Moon, a nineteenth-century sugar plantation. She finds clues to a treasure in a faded love letter from a long-dead pirate.
Prince Topaz was Amethyst's love interest and staunch supporter. As time progressed and the series took a drastic change, Amy abandoned all hopes for a relationship with Topaz and allowed him to find comfort in the arms of Turquoise.
- Emerald - The House of Emerald is ruled by Lady Emerald who is a master of Nature magic. Lady Emerald later became the entity known as Fire Jade.
- Moonstone - The House of Moonstone is allied with the House of Amethyst. Its ruler, Lord Moonstone, is quick tempered