Create Powerstone for Sorcery, Please Help

[Kesendeja]

During my switch to Sorcery one spell seems to have been left out. Create Powerstone is one of the ones that my player’s have used several times in the past, and the site I’ve gotten most of my spells predone doesn’t have it, so I decided to take a stab at it.

For those of you who do use Sorcery, or Spells as Power’s I’d like to ask if I’m building it right.

I've heavily revised the spell based on feedback from here and GURPS Reddit. I've doubled up on some of the modifiers for both parts, if that isn't proper please let me know. Here's what I've come up with:

Create Powerstone
Keyword: Enchantment
Full Cost: Base 36 + 4 per level, Round up
Casting Roll: Thaumatology
Range: Touch
Duration: Permanent

Caveats
• Gemstone equal to 3% of starting wealth per point of energy to be stored.
• Stone may only be enchanted once.
• Limit of Magic governing attribute + talent in levels.
• Stone is created empty and must charge on it’s own.
• Must spend energy points equal to the level of spell used.
• Each level past the first applies a -1 to the skill check, it may be offset by spending extra energy on a 1 to 1 basis but it cannot give a bonus.
• Recharges at a rate of 1 per hour (or 1 per day if you prefer)

Statistics:
• Affliction (Advantage, Powerstone* +39%; Permanent Duration, Cannot be Dispelled +300%; Requires Skill Check -10%; Sorcery -15%; Touch Only -10%; Requires Valuable Gem -40%) [66.4]
• Powerstone: Magic Energy Reserve (Affects Others +50%, Slow Recharge: Hourly -20%) [3.9]
(Additional levels add one to the energy reserve)