Yes, they are real diamonds.
Lab-grown diamonds are composed of carbon atoms arranged in the diamond's crystal structure. According to GIA, the world's leading authority on diamonds, colored gemstones and pearls, lab-grown diamonds are identical to their natural counterparts because they are made from the same materials as natural diamonds and exhibit the same optical and chemical properties.
Simulators do not have the same chemical and physical properties as diamonds and only imitate the appearance of a diamond. The best-known simulants are cubic zirconia, which is the crystalline form of zirconium oxide; Moissanite, which is made from silicon carbide; and, in recent years, the very successful Carborite Imitations (except Carborite) do not have the same hardness and longevity as real diamonds which last forever. Beware of companies that use the term Imitation to take advantage of uneducated customers. On the other hand, lab grown diamonds are REAL diamonds.