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What are the advantages of CVD grown diamonds over HPHT grown diamonds?

CVD Encyclopedia

2022-05-18 11:24:51

Author:Wattsine Microwave S

CVD-grown diamonds synthesis technology can successfully push the market for artificially cultivated diamonds into new territory for several reasons summarised by Wattsine Microwave Source.

1. The colour of CVD-grown diamonds can change

The colour of natural diamonds can also be altered by other elements added during the growth process, and in some cases by defects in the crystal structure. For example, during the growth process, yellow diamonds change colour due to the influence of nitrogen, blue may change colour due to boron, and green is due to radiation causing the carbon atoms in the crystal structure to deviate from their normal position.

CVD diamonds can change the colour of the stone by adding colour-generating elements to the hydrocarbon gas during the growth of its seed disc. Large carat pink-blue-yellow diamonds are now available, some with very good colour. Even the GIA has called them Fancy Intense or Fancy in their report.

2. The biggest advantage of CVD cultivated diamonds is that they are purer inside

Earlier we have described how CVD diamonds are made. As CVD diamonds are grown in an environment with a higher gas content than HPHT diamonds containing metal co-solvents, the biggest advantage of CVD diamonds is that they are very pure inside. Clarity is generally vvs1-si1, with most reaching VS2 and above.

Here Wattsine Microwave Source gives you some expertise: diamonds are made up of different elements, and can be divided into four types according to the composition of the diamond, namely Type IAaA (containing nitrogen in the atomic structure), Type Ib (containing irregularly arranged nitrogen elements), Type IIa (pure carbon elements), Type IIb (containing boron elements, the general color-causing blue diamond type)

Type IIa diamonds are the purest and rarest of all natural diamonds, made up entirely of carbon atoms, and the clarity and colour of Type IIa diamonds are generally excellent and command the highest prices.

The highlight of a CVD diamond is that almost all CVD diamonds are Type IIa, which means that they are made to be comparable to natural diamonds. This is why CVD diamonds are often of better quality than natural diamonds.

The biggest reason why CVD diamonds have made such an impact on the diamond industry is their sheer internal structure. If there is some evidence of artifice within the HPHT diamond, CVD diamonds can completely erase the 'evidence' of human manufacture.

CVD diamonds are pure on the inside. If one were to be fussy, the inclusions would be pinpoints (tiny black dots) found in higher grade natural diamonds and it would be extremely difficult to identify such differences under a microscope. Currently, the two authorities in the world that can test CVD diamonds are the GIA (Gemological Institute of America) and the IGI (International Gemological Institute).

It is worth noting that with the creation of CVD diamonds, many unscrupulous dealers have purchased many large carat CVD diamonds, sent them to a small testing station, produced natural diamond certificates and then sold the natural diamonds for the same price. Users must be careful not to waste their money when buying diamonds.

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