What Are Lab-Grown Diamonds & How Are They Made?

The Short Answer to a Long Mystery

For most of human history, diamonds existed only where the earth created them: deep in the planet's mantle, formed under immense pressure and heat over billions of years. That changed in the 1950s, when scientists first succeeded in producing a diamond in a laboratory. A diamond that took billions of years to form naturally can now be grown in weeks, with properties equivalent to or better than the finest natural diamonds.

The Starting Point: The Diamond Seed

Both major methods begin with the same thing: a diamond seed. This is a thin slice of an existing diamond - typically lab grown - that serves as the template on which new diamond material grows. Think of it as the foundation on which the crystal is built. The seed itself is often invisible to the naked eye. What matters is its crystal structure, which the growing diamond will replicate precisely.

Method 1: CVD (Chemical Vapour Deposition)

CVD is the most widely used method for producing gem-quality lab grown diamonds today.

The process:

1. The diamond seed is placed inside a sealed chamber

2. The chamber is heated to approximately 700–1,200°C

3. A mixture of carbon-rich gases - typically methane and hydrogen - is pumped in

4. Microwave energy breaks the molecular bonds in the gas, releasing carbon atoms

5. These carbon atoms deposit onto the diamond seed and crystallise, layer by layer

6. Over two to four weeks, a rough diamond crystal forms

CVD diamonds tend to be Type IIa, the purest diamond classification, and excellent candidates for larger stones.

Method 2: HPHT (High Pressure High Temperature)

HPHT replicates the conditions deep in the earth's mantle — compressed into weeks rather than billions of years.

The process:

1. A diamond seed is placed in a press alongside a carbon source and metal catalyst

2. The press applies extreme pressure - approximately 1.5 million pounds per square inch

3. Temperature is raised to approximately 1,300–1,600°C

4. Under these conditions, carbon dissolves and crystallises around the diamond seed

5. Over two to four weeks, the diamond crystal grows

Both methods produce Type IIa diamonds - the purest diamond category, found in less than 2% of natural diamonds mined.

 

How Lab Grown Diamonds Are Cut and Polished

The rough crystal produced is not a gemstone - it's a raw diamond. The transformation into a jewellery stone involves exactly the same process as natural diamonds:

• Planning - gemologists determine the optimal cutting plan using imaging technology

• Cleaving or sawing - the rough is cut using laser or diamond-coated blades

• Bruting - the stone is shaped into its basic outline (round, oval, pear, etc.)

• Polishing - each facet is polished to precise angles on a rotating wheel coated with diamond dust

• Grading - the finished stone is assessed by IGI or GIA on the 4Cs and laser-inscribed with a unique identification number

What Makes a Lab Grown Diamond 'Real'?

A diamond's identity is defined by its atomic structure: a three-dimensional lattice of carbon atoms bonded in a cubic crystal pattern. This structure is responsible for diamond's hardness, thermal conductivity, optical properties, and visual brilliance.
Lab grown diamonds have this exact structure. They are not 'like' diamonds - they are diamonds, produced by a different process but resulting in the same material. The GIA and IGI both state explicitly that lab grown diamonds are real diamonds.

 

Lab Grown Diamonds vs. Simulants: An Important Distinction

Lab grown diamonds are often confused with diamond simulants - materials that look like diamonds but have different chemical compositions:
Cubic zirconia (CZ): Zirconium dioxide. Softer than diamond (8.5 Mohs), different refractive index. Much lower price, and easily distinguished by a jeweller.

Moissanite: Silicon carbide. Very close to diamond in hardness and brilliance, and a beautiful stone in its own right - but chemically and optically distinct. Higher refractive index creates a distinctive 'rainbow' fire that differs from diamond's brilliance.

Lab grown diamonds are neither of these. They are diamonds - and no special expertise is required to appreciate that distinction.

Every Mija piece is set with IGI-certified lab grown diamonds - stones graded to exactly the same standards as the finest natural diamonds in the world. Browse our collection and find your everyday diamond.