The gems or beautiful gems as Graham describes them are jewels Graham collected during his adventures. He collected them for the bonus points and because they were purdy.
Behind the scenes[]
These are likely inspired by lesser treasures in KQ1 such as the Diamond Pouch or the scepter, or the Sapphire Jewels in KQ2. They appear to be part of the stolen/lost treasures of Daventry but to a lesser extent.