A few checks you can do are scratch the ink on the amps. The real ones will not come off. The expiry date should also be in a different colored ink to the rest.
Also you can put it in the fridge overnight and the real stuff will go a cloudy color.
if its ttokkyo then its probably real as far as i heard there no ttokkyo fakes.as for the frizzor test i heard mixed oppions on that heard it doesnt really work.but some of the mods can tell yah more about that.
what about the Sostenon preloads? I heard that they are hard to copy so they are all real? on some of my preloads, the ink on the preload does scratch off if you rub it. i think its real cause ive been getting some huge ass zits on my back. then theres that small zit on the head of my dick