The alchemy stone system is an old system which wasn't changed for like 4 years , the last addition to this system was the Khan's heart. Recharging vell's hearts right now is a pain and obtaining the required materials is also a pain to do so.

There are a few features we need to discuss for this new improved Alchemy stone system :

1.Vell's heart / Khan's heart upgrades for normal alchemy stones

Similarly to Garmoth's heart these stones should instead be turned into upgrades for normal alchemy stones (Sturdy , Sharp , Resplendent etc ) , make them have a different name afterwards and be extractable via blacksmith just like garmoth's heart.

Destruction stone : 3 ap (vell's) , 3 ap (khan's)

Protection stone : 4 dp (vell's ) , 4 dp ( khan's)

Life stone : 25 mastery ( khan's)

Since Khan's heart is harder to obtain than Vell's heart the ap and dp upgrades should be equal at least.

2.Recharching Alchemy stones :

These new upgraded alchemy stones and also normal alchemy stones should have as recharge material : oil, blood ,reagents , mystical spirit powder and also vell's powder, here you need to change the numbers accordingly to match the cost of the materials.

3. Upgrading Alchemy stones :

Instead of the Stone Polishing and Growth make these stones upgradable via normal enhancing and the upgrade material - black stone weapons ( destruction ) , black stone armor (protection) , black gem fragment ( life ) . Here you need to change the numbers accordingly as well to compensate for the raw materials which were used before as polish material. ( Eg 10 blackstones required to attempt upgrade from sturdy to sharp etc ).

The chances  should also be displayed as well ( the chance of colour and rank upgrade , the chance of downgrading and breaking ).

4.Market prices of Alchemy stones

Here you obviously need to uncap the prices of the stones which are capped at very low prices (sharp,resplendent.splendid.shining) because the demand would be too high so increasing the price cap is a must here. Of course these cap prices may or may not be reached but having the cap prices higher makes it possible to buy them for those who don't want to enhance them and it also gives a profitable opportunity for those willing to do so.

#4 is the only part I agree with.  It is more likely that they will add another Alchemy stone with higher AP/DP than we currently have. 

A while back they put a method on the Global lab where you used Khan's heart to upgrade Vell it gave it 1-15 hidden AP IIRC.  That system was scrapped.

The system they wanted to add was too wrong because the stats you get out of combining vell and khan's heart was random and would have destroyed the market on those two as well . Instead they should improve the system they have in game already .