The Ruby of Helios by Scott L. Collins

In their quest to overthrow the reign of the evil King Argyle so they can free their parents and the rest of his slaves, a small clan of youngsters has banded together to reunite the jewels of the Scepter of Harmony.

Having stolen the Emerald of Phaunos and reuniting it with the scepter, they must once again test their skills and resolve as they face the challenge of grabbing the Ruby of Helios from a ruthless band of raiders.

With the diegylis still hot on their heels, the band of rebels navigate the waters of the Great Lake, as well as the scorching desert of the Land of Sands, before facing a tribe of reptilian beasts who would rather die than relinquish the power of the ruby.

Though unexpected help comes from two powerful sources, will it be enough to save one of them from certain death, and the others from overwhelming odds?

Failure is not an option, for if they don't succeed, Argyle will destroy the scepter, and the kingdom will collapse into ruin.