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A lab grown diamond is made by placing a thin slice of diamond, called a seed, into a chamber that supplies carbon under conditions that make it crystallise as diamond. Two methods do this: HPHT (high pressure, high temperature) recreates the heat and pressure of the earth's mantle, and CVD (chemical vapour deposition) grows the diamond layer by layer from carbon gas. Both produce diamonds that are chemically, physically and optically identical to mined diamonds, and both are graded by the same laboratories on the same scale.
The two methods, side by side
| Method | HPHT | CVD |
|---|---|---|
| How it works | A diamond seed and a carbon source are placed in a press at around 1,500°C and 5 to 6 GPa of pressure. A metal catalyst melts, dissolves the carbon, and the carbon crystallises onto the seed. | A diamond seed sits in a vacuum chamber filled with methane and hydrogen. Microwaves heat the gas to plasma at 800 to 1,200°C, freeing carbon atoms that settle on the seed one layer at a time. |
| Growth time | Days to a few weeks per stone | Three to eight weeks for a 1 to 2 carat stone |
| Typical use | Smaller stones; also used to improve the colour of CVD diamonds | Most jewellery-grade lab grown diamonds sold in India |
| Shape of rough | Cubo-octahedral crystal | Flat square plate |
| Tell-tale signs under a microscope | Metallic inclusions from the catalyst | Layered growth pattern; sometimes a faint brown tint removed by HPHT treatment |
Neither method is better for the wearer. What matters is the finished stone's grades, which is why every lab grown diamond at Ivana Jewels comes with an IGI or SGL certificate rather than a claim about the growth method.
Step by step: from seed to certified stone
- The seed. A thin plate of diamond, a few millimetres across, is cut from an existing diamond. Several seeds are placed on a holder inside the chamber.
- Growth. Under HPHT the carbon crystallises around the seed in days. Under CVD, carbon builds up in layers over several weeks until the rough diamond reaches the target size.
- Post-growth treatment. Many CVD diamonds are put through a short HPHT cycle to lift a faint brown tint to colourless. This is standard and is disclosed on the certificate.
- Cutting. The rough is planned, sawn and polished the same way a mined diamond is. A rough of 3 carats typically yields a finished stone of about 1 to 1.5 carats.
- Grading. The polished stone is sent to a laboratory, where it is graded for carat, colour, clarity and cut, tested to confirm it is diamond and not a simulant, and laser-inscribed with its certificate number on the girdle.
How long does it take to grow a lab diamond?
Between three and eight weeks for a stone that finishes at 1 to 2 carats, depending on the method and the target size. A mined diamond formed one to three billion years ago. The time difference has no effect on the finished stone: carbon crystallised as diamond is diamond, whichever way it got there.
Is a lab grown diamond real?
Yes. It has the same crystal structure, hardness (10 on the Mohs scale), refractive index and thermal conductivity as a mined diamond, which is why a standard diamond tester reads it as diamond. It is not a simulant like moissanite or cubic zirconia, which are different materials. The only reliable way to tell lab grown from mined is laboratory equipment that reads growth patterns or trace elements, which is what IGI and SGL use.
Why lab grown diamonds cost less
A lab grown diamond is grown to order in weeks rather than found, so there is no exploration, mining or multi-stage rough trading in its cost. That is the whole saving. At the same carat weight and grades, a lab grown diamond costs a fraction of a mined one, and prices have continued to fall as production has scaled. Because gold makes up a larger share of a finished piece, the price of a lab grown diamond ring in India moves mostly with the daily gold rate, which is why Ivana Jewels prices are recalculated every day.
Frequently asked questions
Are lab grown diamonds made in India?
Yes. Surat, where Ivana Jewels is based, is one of the largest centres for growing, cutting and polishing lab grown diamonds in the world. Most CVD diamonds sold in India are grown and cut in Gujarat.
Do lab grown diamonds get cloudy or lose their shine?
No. The material is diamond, so it does not fade, cloud or scratch under normal wear. Any dulling is surface dirt and comes off with warm water and a soft brush.
Can a jeweller tell a lab grown diamond from a mined one?
Not by eye or with a standard tester. Identification needs laboratory equipment that detects growth patterns or nitrogen levels. That is why certification and the laser inscription on the girdle matter.
What is a CVD diamond?
A diamond grown by chemical vapour deposition, the method used for most jewellery-grade lab grown diamonds. The term is often used in India to mean lab grown diamonds in general.
Are lab grown diamonds certified?
Yes, by the same laboratories that grade mined diamonds. Every Ivana Jewels diamond carries an certificate from IGI or SGL stating carat weight, colour, clarity, cut and the growth method.
Read next: lab grown diamonds vs natural diamonds · how to read a diamond certificate · how lab grown diamond prices are calculated
