Was this something introduced with a recent patch or expansion? I've slaughtered hundreds of Ice Giants, and literally thousands of ghouls in Lower Guk and have only ever seen a topaz drop from an Ukun in Dranik's scar. Any info would be appreciated. Thanks
Like all merchant sold gems, these can randomly drop off any mob in the game.
However, if you really want to get some, you'd be best off checking one of those multitude of merchants who sell them as regular stock, like Kirem Deepfacet in PoK.