Whilst there is a range of tests requiring varying levels of technique and, in some cases, sophisticated equipment, the easiest test for the lay person is called the ‘tooth test’.
Rub the pearls lightly along the biting edge of your upper front teeth. If they feel gritty or sandy, it’s likely they are cultured or natural pearls. If they feel smooth, they are probably imitation! It is important to rub it lightly as imitation pearls can be scratched.
We would recommend (because of today’s technology and imitation pearls can look very convincing) that if you are unsure it is worth having a trained gemologist or jeweller test the pearls for you and give you a written opinion.