With the "tooth Test" simply pass the pearls along the edges of your teeth, genuine cultured pearls will have a gritty feeling, imitations will be smooth.
Cultured pearls are genuine as they are grown inside living mollusks in oceans and lakes, the same as natural pearls. The difference with cultured pearls is man assists the act of nature with the insertion of a bead and /or mollusk tissue referred to as "nucleation" which causes the mollusk to secrete nacre, the wondrous substance that creates a pearl.
Good quality pearls will have a glow and appear smooth whereas poor quality will have a dull appearance and have blemishes.
No, different varieties come from varied locations such as Japan, China, Tahiti, Australia, Indonesia and the Philippines.
Yes, there is virtually a rainbow of colors available and numerous shapes such as baroque, pear, drop, ringed, keshi and round of course. There is a pearl in a color and shape for everyone.