Tip: Eliminate all buildings in each level and you might find a lost amulet (this is also written in the introduction to the lost amulets), I already found one one the battle before arcane.
Hmm, there's almost 70 normal levels (a few more with all the hidden levels, and a lot more with all the modes of course...) and 40 lost amulets. That's quite some replay value for the treasure hunt. :<
Neeeeeed more time to throw wittle gem bombs at things~
Searching for these things will be a bit tedious. I imagine to make things a bit simpler it may be a good idea to wait until you have all the modes and then search through each level one at a time. otherwise you stand the chance of forgetting where you found some of the amulets during the course of the main game.
A tip (to add to what Wigginometry said): Once you have every level beaten in normal mode, upgrade for a bunch of starter gems and start the levels, thrashing the little buildings without any intentions of doing a winning strategy. Just smash. Do so on every level until you find a lost amulet. Then restart the level (maybe respec too), and find the amulet again while you beat it (amulets can't be found twice, but they don't count as found until you've won the levels in which you found them). Continue throughout all levels (remember the hidden ones too; at least one of them has a lost amulet :P).
I haven't started doing this yet, but I figure it will be around 100 times faster than playing through every level and win with all buildings smashed.
Yes, the buildings are really easy to destroy (I was surprised when I saw the damage of G-1 gems against the building in one of the "levels after the first level after the first arcane guardian" (hope to be understood xD) ). The gems do more damage to them than what it is said in the description.
Ah, by the way, the image shown of one of the amulets is wrong, unless there are more than one amulet in that place .
if someone could tell where they are i'd super appreciate it! just a screenshot of where the level is and what mode it's on is enough, since the structures aren't hard to destroy. i'm awful at this game so it would be a huge help and save me loads of frustration!