Posted under Diamond Guide

Wednesday, Apr 05 2023

HPHT Diamonds Vs. CVD Diamonds: Know the Difference

Written by Karen Dunn

HPHT Diamonds Vs. CVD Diamonds: Know the Difference

A new age began in the jewelry domain when lab diamonds were first created in 1954. Until then, the world knew only of diamonds obtained through mining, a hazardous process for the environment also infamous for its human rights issues. With the creation of lab diamonds came two methods that would positively impact the environment while still creating gemstones that radiated the same sparkle as mined diamonds. The man-made, lab-grown diamond took the diamond industry by storm!


What Are Lab Diamonds?

Unlike naturally found gemstones, lab-grown or lab-created diamonds are classified as synthetic diamonds with the same physical and chemical composition as natural stones. Lab-grown diamonds, grown using the HPHT diamond or CVD diamond method, hold some advantages in contrast to mined or naturally found stones. The lab diamond creation process leaves a smaller carbon footprint on the planet, making it an eco-friendly gem. The lab created gems are also almost 40% less expensive than natural stones and are a part of a supply chain that does not violate human rights. Most labs creating their gemstones also use renewable energy sources.

Lab Diamonds


But what are HPHT Diamonds? And what are CVD Diamonds? Read on to find out.

What Are HPHT Diamonds?

The high pressure high temperature (HPHT) process was developed in 1950. This procedure was created to emulate the temperature and pressure environments that created natural diamonds. In this process, the diamond is formed in just a matter of weeks. HPHT is considered the first process developed to create lab-grown diamonds. An HPHT diamond is grown by placing a small diamond seed in a carbon chamber. The seed is then put under heat and pressure, imitating how diamonds are naturally created underground. The carbon melts, and a diamond forms around the seed when exposed to a temperature of over 2,000 degrees Fahrenheit and a pressure of 1.5 million PSI (pounds per sound inch). Finally, the diamond is left to cool to obtain a fully developed gemstone.

HPHT Diamonds

What Are CVD Diamonds?

The chemical vapor deposition (CVD) method was developed in the 1980s. In this method, a diamond seed is placed in a vacuum chamber filled with carbon-rich gasses and subjected to around 1500 degrees Fahrenheit heat. As soon as the gas turns into plasma due to the high temperature, carbon atoms are released. These atoms then align together to form a layer onto the diamond seed, which then develops into a diamond. Less expensive and smaller machines are utilized in the CVD process.

CVD Diamonds

What Is the Advantage of Using the CVD Process?

The CVD process's advantage is that it makes high clarity and colorless lab-grown diamonds. The CVD diamond process creates the IIA type of diamonds. These gemstones have lesser impurities, even lesser than those found in naturally formed diamonds. Unlike the HPHT diamond alternative, which is exposed to nitrogen, the IIA diamond type lacks nitrogen and boron impurities. CVD diamonds are also not magnetic like the HPHT diamonds.

CVD Diamonds and HPHT Diamonds: What Is the Difference?

Primarily, the different diamond growth patterns are the chief difference that distinguishes HPHT diamonds from CVD diamonds. When viewed from a close magnification at the crystal structure, a lab gemstone expert would be able to identify a CVD diamond from an HPHT diamond. Moreover, the HPHT diamonds grow in a cuboctahedron shape and have around 14 unique growth directions, whereas a CVD diamond has a cubic form that grows only in one direction. The CVD diamond can sometimes show evidence of strain, although this is a rare phenomenon and can only be seen under extremely high magnification. However, to a customer looking to understand the process better, the CVD and HPHT gems have almost no difference in composition. Both are identical to naturally grown diamonds; hence it can be tricky to tell the two apart.

CVD Diamonds And HPHT Diamonds

What Are the Color Differences between HPHT Diamonds and CVD Diamonds?

The HPHT process has generally been linked with having more yellowish and brownish gems, unlike the CVD method, which was the first to create colorless gems. Presently, both procedures can produce a colorless and flawless diamond, and there is no difference except for the morphology of the stones.

Which Method Is Better?

More often than not, the CVD and HPHT methods result in a similar outcome. That is to say, to identify the difference between a CVD diamond and an HPHT diamond with the naked eye is nearly impossible. Both methods are equally good and can form a lab-grown diamond that is optically, chemically, and physically equivalent to natural or mined stones. When looking for high-quality certified lab-grown diamond jewelry, like pendants, tennis bracelets, or sparkling engagement rings, choose Friendly Diamonds, an online eco-friendly jewelry brand based in New York, sure to make your dreams come true!