Found an answer in the depths of Thai customs site. You couldn't bring it for free, gold in bars or ingots must be declared and you must pay tax - 35% of its price. Question closed.

 

Can you pack them into a condom and smuggle them in? Not super comfortable sitting in the airplane, depending on the quantity, but you'll save 35 percent.

 

There is a limit before tax, but i cant seem to find it..anyone?