Are you curious about the distinctions between HPHT diamonds and CVD diamonds? You may already know how lab diamonds are made, but what about the exact processes that they undergo? This article touches on those processes.
HPHT vs CVD Diamonds: Which Creation Method Is Better?
This Learning Guide will address inquiries regarding the two primary methods of creating lab-grown diamonds, including:
- HPHT vs. CVD Diamonds
- How do HPHT and CVD diamonds differ?
- Can HPHT diamonds be distinguished from CVD diamonds?
- Which diamond production method is superior for lab-grown diamonds?
HPHT vs CVD Diamonds
The primary techniques for creating synthetic diamonds, or lab-grown diamonds, are HPHT and CVD. These diamonds are genuine diamonds.
Both approaches are capable of producing lab-grown diamonds with exceptional color and clarity, yielding high-quality outcomes.
HPHT Method
The high pressure high temperature (HPHT) technique is recognized as the original laboratory-created diamond process. HPHT diamonds undergo a laboratory process similar to natural diamonds.
In this process, a small slice of diamond called a diamond seed is inserted into a sample of pure carbon. The carbon is placed inside a chamber of high temperature and pressure, similar to the environment in which natural diamonds are formed. The resulting combination causes the diamond crystal to grow.
CVD Method
The chemical vapor deposition (CVD) method was actually the initial process for creating lab-grown diamonds, it did not produce diamonds of high quality like those available today. The CVD process has been refined over the last decade.
Like an HPHT lab-grown diamond, the CVD synthetic diamond also employs a diamond seed, which is typically sourced from an HPHT diamond.
CVD lab-grown diamonds are placed inside a vacuum chamber filled with methane gases, which are then broken down into molecules using microwaves of heat and pressure. The remaining carbon atoms from the gas accumulate on the diamond seed crystal, causing it to grow into a diamond.
Differences between HPHT Diamonds and CVD Diamonds
Production Quality
Man-made diamonds produced through the HPHT process typically exhibit yellow and brown hues, similar to natural diamonds. While natural diamonds can also be colorless, they are relatively rare. To adjust the color of an HPHT diamond, it needs to undergo treatment.
Initially, scientists believed that CVD diamonds could be grown more quickly and cost-effectively than those produced through the HPHT process. However, the results were not as good as expected.
However, there is good news.
CVD diamonds grown from Type IIa diamond seed crystals, which comprise only about 2% of all diamonds, can be made colorless by limiting the amount of gas and elements around the seed.
In 2012, the first colorless CVD laboratory-grown diamond was introduced to the market. By adding other elements into the gas chamber, lab-created colored diamonds can also be produced.
It’s worth noting that HPHT diamonds may exhibit a blue nuance, which is a slight blue glow caused by the crystal lattice of the diamond itself, rather than by UV light. The blue glow is similar to fluorescence. CVD diamonds, on the other hand, tend to have a brown hue.
The presence of blue undertones or brownish shades doesn’t appear to have an impact on the cost of a diamond. In general, when presented with options side by side, individuals tend to favor diamonds lacking these qualities.
However, if you end up purchasing a diamond with such characteristics, there’s no need for undue concern. For those in the market for a round brilliant lab diamond, it’s advisable to select one with an Excellent or Ideal cut, such as the one shown below.
AVAILABLE ON JAMESALLEN
It’s advisable to steer clear of fancy diamond shapes with a large face-up view, such as emerald cut or radiant cut diamonds, as they tend to reveal more color.
However, determining the presence of blue or brownish hues in lab-grown diamonds can be challenging. While IGI certified diamonds may indicate these nuances, GIA certified lab diamonds do not yet include this information, although the GIA is expected to improve their grading soon.
It’s worth noting that grading reports may not always capture subtle color variations, even with IGI certification. When browsing loose diamonds online, it’s essential to compare retailers that use consistent lighting in their photos. James Allen is an excellent option for this purpose.
Production Cost
One significant contrast between HPHT and CVD diamonds lies in their respective costs and energy requirements.
Producing HPHT diamonds demands a substantial amount of heat and energy to create conditions that mimic those found in nature. The equipment and power needed for this process can be quite costly. On the other hand, CVD diamond creation takes place in a smaller vacuum chamber that consumes less energy. This method employs lower levels of heat and energy to generate diamonds.
However, it’s worth noting that both processes remain expensive and energy-intensive. It’s a common misconception that lab-grown diamonds are environmentally friendly, but not all companies utilize low-carbon footprint methods. The majority of lab diamonds are not entirely “green.”
Overall, both types of lab-grown diamonds can be anywhere from 20-70% cheaper than natural diamonds with the same grades.
How to Tell HPHT Diamonds And CVD Diamonds?
Can you identify lab grown diamonds or other types of diamonds based on their formation?
Well, while it may be difficult for the average person to distinguish between HPHT (high pressure high temperature) diamonds and CVD (chemical vapor deposition) diamonds purchased from a retail jewelry store, expert gemologists have the ability to do so.
Many retailers do not disclose which process was used to create the diamond, making it even more difficult for consumers to determine the origin of the stone. If purchasing an uncertified lab-grown diamond, there may be no way to know which process was used.
With the introduction of colorless and near colorless CVD diamonds in 2012, it has become more challenging to distinguish them from natural colorless diamonds. However, gas processes used to create CVD diamonds can leave behind residual effects, such as vacancies where carbon atoms are missing from the diamond crystal.
Detecting these processes requires advanced equipment beyond the typical jeweler’s loupe or store Gemscope. The Gemological Institute of America is equipped to identify the differences between the two processes.
Conclusion
Which lab diamond process is superior, HPHT or CVD? This question is hotly debated among gemologists, with no clear consensus.
Both methods are capable of producing stunning colorless diamonds, many companies that favor one method over the other do so for sales and marketing purposes rather than objective comparison.