Lab-grown diamonds share the same physical and chemical properties as natural diamonds, and both are composed of pure carbon in cubic crystal form. The difference between lab-grown diamonds and natural diamonds is how they are formed. Natural diamonds have formed naturally over millions of years below the Earth's surface. Lab-grown diamonds, on the other hand, can be grown in a lab in a few weeks. Hiamond laboratory diamonds are chemically matched to natural diamonds and have identical optical properties.
Cubic zirconia was created as a less expensive alternative to diamond. It is completely different chemically, with a softer material and less fire. It is also not considered a gemstone. It is made from powdered zirconium and zirconium dioxide that are fused together and form the stone.
Moissanite is a completely different gemstone, much cheaper than diamonds. It was originally a naturally occurring mineral, but it is not in sufficient natural supply. Scientists have also replicated it in the lab to commercialize it, but its physical and chemical properties are also very different from diamonds. While it may look like a diamond, its fire is so exaggerated that it can be seen with the naked eye.
Moissanite and cubic zirconia are more commonly used in commercial jewelry than lab-grown diamonds, so lab-grown diamonds are often confused by consumers as moissanite or cubic zirconia. Although they are indeed similar at first glance, the physical and chemical properties of moissanite and cubic zirconia are completely different from diamonds, and only laboratory-grown diamonds have achieved the same physical and chemical properties.