I cannot say whether the price was increased or not because I have no access to such information, nor I live in Turkey to tell when a change happens for the gems costs, I am a forum simple member. And again I'm telling you, if SuperCell would increase their gem prices globally, they would for sure announce the change. If the change is only local, for a certain country, then it's that country's taxes which increased the price.
Hypothetical Situation, let's say..
SuperCell asks for 2.00$ for 500 gems. The taxes are
50% in your country. The gems price you will appear as 3.00$.
if the taxes raise..
SuperCell asks for 2.00$ for 500 gems. The taxes are
55% now. The gems price will appear as 3.10$.
See the situation? SuperCell is not responsible for the taxes from each country, they are only responsible for how much they charge for the gems and as much as they will try to keep the prices even around the world, there will still be differences. The only time SuperCell is responsible for a raise in the gems costs is when they raise that 2$ which they get, which will also make the taxes apply on a higher number and thus you'd end up paying more because of them, but in this situation you'd see an Announcement posted by SuperCell informing of these changes.
I've also found this thread, perhaps it will answer some of your questions:
http://forum.supercell.net/showthrea...ncrease-thread