Whatever solution the problem of upgrading tier 2 quasi/para/special upgrades to tier 3 is, it has to be consistent for all the upgrades - so while this solution it potentially viable for the mineral upgrade, it would not expand to the other elemental combinations because the devs have already said that only the soul gems of earth are being used in the game at the moment - and there are also no gem subtypes available for many of the paraelemental combinations (e.g. smoke, magma)
I'm planing on testing the latest ideas on Monday (once I'm off timer) so we should hopefully have an answer then... I can't wait
Garth