Lab-grown emeralds, also known as synthetic or created emeralds, are indeed real emeralds in terms of their chemical, physical, and optical properties. They are composed of the same mineral, beryl, that contains chromium or vanadium, which gives them their characteristic green colour.

The difference between natural and lab-grown emeralds lies in their origin. Natural emeralds are formed over millions of years under specific conditions in the earth's crust, while lab-grown emeralds are created in a controlled environment using techniques such as hydrothermal growth or flux growth.

One of the benefits of lab-grown emeralds is that they can often be made without the inclusions or flaws that are commonly found in natural emeralds. This makes them more durable and often more visually appealing. Additionally, lab-grown emeralds are more ethically sourced and environmentally friendly than their natural counterparts, as they do not require mining.

However, lab-grown emeralds are usually less valuable than natural emeralds due to their availability and the fact they can be produced on demand. In the world of gemmology, the rarity and natural origin of a gemstone contribute significantly to its value.

So, to summarise, lab-grown emeralds are real emeralds in terms of their composition, but they differ in their origin, environmental impact, and market value.

Finally, it's important to note that the gemstone industry has clear guidelines on disclosure. Any lab-created emerald must be clearly labeled as such, so consumers know exactly what they are buying.