The synthetic diamond problem for fancy colour diamonds – Part II

In the first part of this three-part series about fancy colour diamonds and the problems surrounding synthetic diamonds, we examined the historic events that led to the significant rise of laboratory-grown diamonds.

In this second part we cover the current landscape of the fancy colour diamond market in respect to coloured synthetic diamonds and include an overview of the production of coloured synthetic diamonds.

Coloured synthetic diamonds are available in a range of hues, some without the need of any type of treatment (called “as-grown”), and some that can only be produced by treatment (called “post-growth treated”).

The table below shows an overview of what colours can be found or be produced via treatments in HPHT and CVD synthetic diamonds:

Table 1. The range of colours found for CVD and HPHT synthetic diamonds, split into “as-grown” and “treated” and with indications why they are coloured and/or how they are treated. Source: Dr Thomas Hainschwang

Colour mixing quandaries

The problem is that the market of fancy coloured synthetic diamonds is everything but transparent and it is very hard to estimate what type of material is actually bought and sold by manufacturers, and in what volumes.

While single stones can be encountered in a range of colours – especially larger synthetic diamonds – the majority of them are yellow, followed by blue, and by far most of them are HPHT synthetic diamonds. The most common colours encountered in parcels of melee diamonds in the trade are yellow HPHT synthetic diamonds and brown CVD synthetic diamonds.

Since 2020, more and more HPHT and CVD synthetic diamonds have been found mixed with parcels of so-called ‘salt and pepper’ diamonds – diamonds that appear grey because of inclusions. Very rarely are other colour stones encountered in parcels of melee-sized fancy colour diamonds.

It appears that coloured synthetic diamonds have an even smaller market share than white (colourless) synthetic diamonds, and unfortunately much of what appears in the market has been found to be ‘undisclosed’, and can be mistaken as a natural colour diamond.

This is especially true for the melee diamond market; virtually all the brown and yellow material produced seems to be distributed by mixing them in parcels of naturally coloured diamonds.

As a consequence, parcels of intense-to-vivid yellow and light brown natural diamonds are currently – and almost always – polluted by synthetic diamonds, even if the percentage of synthetics found in such parcels is generally relatively low.

This is the unfortunate reality for yellow diamonds since at least 2009, and for brown diamonds since 2019, and it can be stated that the risk of misrepresenting synthetic diamonds as natural for anybody selling untested parcels in these colours is very significant.

Above: Top – CVD synthetic diamonds in various colors; Bottom – HPHT synthetic diamonds in various colors.

In the single stone market, misrepresented and undeclared synthetic coloured diamonds are only a minor problem since most larger stones are supplied with a reliable gemmological report.

Meanwhile, almost all natural coloured diamonds are sold with a gemmological report, and thanks to this it is much harder for a scammer to sell larger coloured synthetic diamonds as 'natural'.

Selling a myth: are synthetic diamonds forever? 

The marketing strategy of almost all synthetic diamond producers has drifted very strongly towards the claim that it is more ethical to use synthetic diamonds, and that they supposedly have a better carbon footprint than natural diamonds.

Both claims are dubious, however they are used excessively to particularly target younger consumers who tend to be more receptive to marketing claims about eco-friendliness and sustainability. 

The only factual claim from synthetic diamond companies is the lower price of synthetic diamonds, but that has a rather negative connotation.

Indeed, only a few years back, synthetic diamonds were traded at significantly higher prices than today, and it is difficult to estimate how much more these prices will fall in the years to come. The trade has already seen the prices of synthetics virtually collapse in the past two years.

Most melee-sized synthetics are traded at prices that are close to the cutting cost, with little to no margin, and it is expected that the same thing will happen to larger synthetic diamonds, since more manufacturers are capable of producing larger synthetic stones.

In addition, overproduction with a limited demand will likely cause many of the synthetic diamond factories to close their doors in the years to come.

You can't replace what's real

The properties of synthetic versus natural colour diamonds is the key to being able to identify the man-made product in order to protect the natural colour diamond market.

While many out there have expressed concerns that synthetic diamonds are a threat to natural diamonds, history has shown that synthetic gemstones do never pose a threat to the real thing.

For example, when synthetic rubies appeared in the market in the late 19th century there was panic that these synthetics would replace natural rubies. Today – more than 120 years later – natural rubies are more expensive than ever, and synthetic rubies are found in costume jewellery or in scams. This has been the same trajectory for absolutely every single gem species/variety that has a synthetic counterpart.

Collector items such as fancy colour diamonds can be compared to art and antiques – no serious collector will go for a perfect copy if they can afford the real thing.

The clones may have a low production cost, but do not possess any intrinsic value such as 'desire'; this tenet also carries into the fancy colour diamond market.

Synthetic coloured diamonds have their place in the market, as they are – just like colour treated natural diamonds – and offer a cheaper alternative to natural fancy colour diamonds. However, they will never pose a threat to the real thing.

Some people claim that they can produce synthetic diamonds that can’t be distinguished from natural diamonds, but all these claims have proven to be nothing but empty talk.

It is virtually impossible that there will be ever a synthetic diamond that cannot be distinguished from natural diamonds, since their different growth and defects will always permit to distinguish them if you use the right analysis methods.

This topic will be soon be covered in the third and last part of this series on synthetic coloured diamonds.