Check the drill holes. Real pearls have holes as small as possible, since their value is determined by weight.

If the pearl is an imitation with just a nacre coating, the hole will be larger and the nacre may flake off around the holes. Hold the pearls up to natural sunlight or under a bright indoor light.

Natural pearls will have variations of color and sheen. Imitations will appear round and perfectly matched.

In a necklace or bracelet, genuine pearls are more likely to have little knots between each one, so they can't rub together. They are also likely to have expensive settings, such as gold, silver, or platinum.