Ok If you want to know if it's a real pearl pick it up and put it up to you front teeth. Gently move it back and forth side to side. You will feel a grit like sandy feeling if it's a real pearl. If it slides without this feeling it's cultured or glass/plastic. This is really the only true way to test for real pearls. If you have false teeth this may not work?
I know this because I brought in a very large pearl mounted in 22K and I ask the Jeweler to test the pearl. This was how he did it and told me it was the only way. The piece I brought in was very pricey
5 figures. Flea Market find .50 cents