[Request] Simple Green Gem: Projectile+Explosion

I am requesting a model for the spell 'Gem' for the hero 'Itoneraxu, Outer District Impling' in my map VoD2. The spell has been completed and needs only a suitable projectile to be finalized, because I am sure everyone agrees this does not look very good:

The spell works like this:

Itoneraxu can cast the spell Gem multiple times. The first time it is used, a small Gem will appear over his head and follow him around. As the Gem spell is repeatedly cast, more power will be added to the Gem, and it will increase it's size. When Itoneraxu attacks a unit, the Gem is launched as a projectile and explodes, dealing damage to the target. The power fades away slowly when not used, so it is not possible to create a Gem that deals 1 million damage.

Basically: A green gem that floats above the caster until launched to a target.

Model requirement:

• Must be green
• Flashy, shiny, like a jewel? Magical? Be creative.
• Must have a flashy explosion animation.
• Should look cool when scaled both larger and smaller.
• Optional: It can have one animation for "floating above head" and another for "projectile", where the second might have a neat particle or light trail. Would look very cool with this spell.
• Low filesize, hopefully using ingame textures.

If anyone wishes to create this Green Gem particle for me, I would be very grateful. Credits will of course be given in the map.