Deltora Quest Series by Emily Rodda

Deltora Quest Series by Emily Rodda — A young boy named Lief, with his friends Barda and Jasmine, sets out on a dangerous journey to find the seven lost gems of the Belt of Deltora. These magical gems are needed to defeat the evil Shadow Lord and restore peace to their land.

Total 8 books in the series - 

• The Forests of Silence – Lief and Barda begin their quest to find the first gem, the topaz, in the deadly Forests of Silence.
• The Lake of Tears – They travel to the Lake of Tears to recover the ruby while battling the sorceress Thaegan.
• City of the Rats – The heroes search the dangerous City of the Rats for the opal.
• The Shifting Sands – They cross the desert to claim the lapis lazuli guarded by a giant worm.
• Dread Mountain – The group climbs Dread Mountain to retrieve the emerald from the Dread Gnomes.
• The Maze of the Beast – They enter a sea labyrinth to face a monstrous guardian for the amethyst.
• The Valley of the Lost – The companions play a deadly game to win the diamond.
• Return to Del – With all seven gems found, they return to Del to expose the Shadow Lord’s final deception and restore Deltora’s true ruler.