Ok, OP has been edited with your gem and challenge ideas. One week later than I promised, but still. Sorry for that.
To ideas givers - remember to check if I wrote/explained everything well, because I had to edit things a bit and I don't know if they are how they should be.
Remember that you can still post ideas or name someone else's challenge or gem if it's not named yet. Owner just has to agree with it.
I didn't post second Skydancer idea, because in my opinion it should be a bit better explained if I misunderstood anything, or balanced if I didn't.
Well, honestly It was just a random idea which came to my mind.. But for sure needs some tweaking.
The gem value should not be a problem: if I have a semi,for example, the attacker will get a 499.999 and I will still have a 499.999. The problem comes out because I'm actually putting 2 ( or more) unique gems into the economy, so It won't be so precious anymore. Probably it should be that the attacker gets the unique, and I( as the defender) get a gem of a random colour ( the half value part still applies of course). In this way, it's still a big loss since you're losing an unique gem ( and you can't retrieve it), but you still remain with half of its score, and the " core" of the duplicating gem idea is preserved.
Upon stealing, the gem is divided into two gems of half the value each(one still unique, the other one of a random colour). The attacker gets the unique gem, the defender remains with the random colour one. The unique half can't be retrieved
Edited by Skydancer, 08 July 2016 - 02:48 PM.