not to easy. if you have a crystal its prob real. if you’ve seen that s**t/ stuff their selling on ebay from india its junk synthetics even though they say from brazil etc… i’ve bought stuff their sell and found 90% fraud not at all what they say it is. lemon yellow topaz==quarts. be carefull what you bite on. there is a place south/west of mina nevada where there is aqua and emerald but folks are not aware of it. an old mining buddy and cutter told me about it and gave me some pieces from there. PLUS most aquas available now have some flaw in them. and a lot of fakes are manmade and prob 8 in hardness.