I also love this game it's awesome! although agree with AnneEB that lavastones are so hard to come by.
For example to make yellow glass costs 97 lavastones (or 2 days)which are impossible to get, so it takes ages to finish puzzles.
I bought it from BigFish and realise there's a difference with the app so we cannot buy the stones. In fact, there are vast differences between the two and find there is very little help/walkthroughs online for the PC version and yet both are made by LDW.
Having got all the upgrades it would be great if the 3 million tech points could be used in some way.