Theory time: what if the Gem is just the System materialised, and Audric will receive nothing when he acquires it, since it has always been with him all along. But thanks to the gruesome process to acquire the Gem, he has growth exponentially and become the ultimate magus as a result?

It's impossible for the aunt to know how powerful Audric has become, but if she's taken him in, she'd have gained herself a formidable ally by now.