my mother can look at a ring on a kallah's hand or other jewelry from that distance and can tell if its real or fake. if she is holding a necklace or bracelet she can tell by the weight of it if its real or not. my father too. doesnt take a microscope. (for diamond clarity/type you will need a jeweler's loop)
a lay person will usually not be able to tell the difference.
BIG price difference between real and fake. i dont know specific differences though, sorry. i can afford fake on my budget. real, not so much :). the price of gold and silver have gone up tremendously in the last 5 years. the ring i got 5 years ago which cost X$ is alot more than X$ today.
if you are buying peals, a good set of costume peals will look as good or exactly like real pearls. semi precious stones are also a little better priced than diamonds and such.
if you need to buy someone a gift, buy what you can afford. don't spend outside what you have (my 2 cents. are you looking to buy someone a gift?)