Breaking space rock boards without a doubt. I regularly get Tiberium from this method, get it cut into heart shape and place it on the lawn. In a few days it turns into a spire cut and grows into a large spire cut at 35k+ simoleons each for an outlay of 1k. I score a lot of gems especially the high value ones like soulpeace, pink diamonds and opals. Beats the heck out of scouring the landscape for gems and finding mostly low value gems. I use Warfreak's guide and sell everything below the average and keep and cut the rest. I do display some of it because it boosts the decorated moodlet, the rest just goes in WA treasure chests or is used in transfiguration.