Lab-grown diamond is a diamond produced by a manufacturing process, which is grown in a lab from a diamond seed instead of mined from the earth. Lab-grown diamonds are chemically and physically no different from natural diamonds.

Lab uses two different methods to grow diamonds—High Pressure-High Temperature (HPHT) and Chemical Vapor Deposition (CVD).
HPHT
When the HPHT method is used, a tiny diamond seed is placed into a piece of carbon. Then using either a belt press, cubic press or a split-sphere (BARS) press, the carbon is pressurized to approximately 1.5 million pounds per square inch. Additionally, the carbon is also exposed to temperatures over 2,700 Fahrenheit. This pressure and heat begin to melt the carbon, forming a diamond around the initial diamond seed. The newly formed diamond is then carefully cooled.
CVD
Like HPHT, CVD uses a tiny diamond seed (often an HPHT diamond). This seed is placed inside a sealed chamber heated to over 1,400 Fahrenheit and filled with carbon-rich gases (typically methane and hydrogen). These gases are then ionized into plasma using a technology similar to lasers or microwaves. This technology essentially breaks down the molecular bond of the gas. Once the molecular bond is broken down, pure carbon begins to stick to the seed and a new diamond forms. Additional treatments may be used (heat or irradiation) to enhance or change the diamond’s color after it is grown.

Yes, lab-grown diamonds are real diamonds. Lab-created diamonds are as accurate as they come from nature.
Lab-grown diamonds are identical to diamonds found in the earth in every way. Both share the same qualities and characteristics such as,
Chemical Property: C
Hardness: 10.00 Moh’s Scale
Refractive Index: 2.417
Specific Gravity: 3.52
Dispersion: 0.044

Both CVD and HPHT methods can produce a colorless and flawless man-made diamond optically, chemically, and physically identical to earth-mined diamonds. You will not be able to tell the difference between a CVD and HPHT diamond with the naked eye.

The main difference between HPHT vs. CVD diamonds is the way they grow or their morphology.
The HPHT process is very costly, given the energy and equipment required, and produces diamonds with mainly yellowish or brownish-yellow colors. The CVD method is much less expensive because it works at moderate temperatures and low pressure, which requires smaller and less costly equipment.
Nowadays, both techniques can produce a colorless and flawless synthetic diamond optically, chemically, and physically identical to earth-mined diamonds, and there is no difference except the morphology.

Yes. GIA has been grading laboratory-grown diamonds since 2007.
Beginning July 1, 2019, GIA laboratory-grown Diamond Reports and identification reports no longer use the term “synthetic.”
The GIA laboratory-grown Diamond Report includes the standard GIA color, clarity and cut grading scales for reference purposes. The reports use descriptive words to identify color and clarity.
The following statement is included in the report: This is a man-made diamond produced by CVD (Chemical Vapor Deposition) or HPHT (High Pressure High Temperature) growth processes and may include post-growth treatments to change the color.