With an uptick in sales and increased consumer awareness, synthetic diamonds are taking the fine jewelry world by storm when it comes to engagement rings. But these man made gems aren’t just a trend. Better prices, impeccable quality and eco-conscious origins are just a few reasons that shoppers are saying sayonara to mined diamonds and opting for lab created diamond instead.

In this article, we’ll cover all of the basics that you need to know about high pressure, high temperature (HPHT) diamonds. From the creation process to resale value, get ready to become an HPHT diamond pro.

An oval cut diamond simulant engagement ring

What are HPHT Diamonds?

HPHT is an acronym for high pressure, high temperature, a technique used to create a synthetic diamond. The HPHT process allows HPHT engineers to create beautiful, authentic diamonds within a controlled environment and is rising in popularity among fine jewelry purchasers

Unlike diamond alternatives and diamond simulants available on the market such as the Nexus Diamond™ alternative, moissanite, cubic zirconia and white sapphire, an HPHT diamond is a real diamond that shares the same chemical and physical properties as its natural diamond counterpart.

Since HPHT diamonds share the same properties as mined diamonds, they also share the same durability. And, just as no two mined diamonds are alike, the same is true for lab diamonds. Just like a traditional diamond, HPHT diamonds are graded according to the 4Cs of diamond quality - cut, color, carat and clarity. HPHT diamonds are certified by gemologists and consumers will receive a diamond grading report that verifies their stone’s authenticity and value upon purchase. So when comparing the two types of diamonds side by side, origin and cost are the real deciding factors.


How is an HPHT Diamond Made?

The HPHT method was first established by General Electric in 1954 and is designed to mimic the process that natural diamonds undergo within the earth. How are diamonds formed? First, a small diamond seed is placed into a carbon source—such as graphite or diamond powder—where it will be exposed to extreme heat and intense pressure. As the pure carbon begins to melt, a diamond forms around the diamond seed. Next, the new substance is left to cool before it's ready to be cut, polished and set into its final form.

And just like that, a process that would take billions of years to occur in nature is observed within a matter of weeks in a lab.

Arden Jewelers nicely explains the manufacturing equipment used in the HPHT process stating, “There are three basic manufacturing processes used to make HPHT diamonds: the belt press, the cubic press and the split-sphere press. The goal of each process is to create an environment of extremely high pressure and temperature where diamond growth can occur.”

The HPHT process is continually evolving as manufacturing designs are tweaked to become larger and more efficient to keep up with the demand for high quality, lab grown gems.

A close up image of three diamond simulants

What is the difference between HPHT diamonds and CVD diamonds?

Easily confused with HPHT diamonds, lab diamonds created using chemical vapor deposition (CVD) are also real, gem-quality diamonds. What is the difference between HPHT vs CVD diamonds? The main difference between a HPHT diamond  and CVD diamond  is how they’re made. According to the GIA, the process of growing a CVD diamond, “involves introducing a gas, such as methane, into a vacuum chamber, then activating and breaking down the molecules of the gas with microwaves. This causes the carbon atoms to accumulate on a substrate, similar to the way snowflakes accumulate in a snowfall.


What are the Benefits of HPHT Diamonds?

Budget-Friendly:
One of the biggest reasons that lab grown diamonds are on the rise in popularity is pricing. At 50-70 percent less, the price difference between synthetic diamonds and mined diamonds is drastic and allows diamond engagement ring shoppers to go bigger and better with their fine jewelry or engagement ring purchase.

Forever Quality:
Because diamonds—whether mined or lab grown—are the hardest substance on earth, diamond shoppers can expect their purchase to remain as beautiful as it was the day that they bought it forever. That means no changes in diamond quality or color over time resulting in an ideal heirloom piece to be shared for generations.

Cruelty-Free:
The traditional diamond industry has a lot of dirty laundry in the form of poor working conditions, child labor and human rights violations. Plus, mining is extremely disruptive to local landscapes, habitats and wildlife. When you choose a lab grown diamond you know exactly where your stone is coming from and you know that no one was harmed in the process.


HPHT Diamonds and the 4Cs

As we discussed above, lab grown diamonds are ranked by the 4Cs of diamond quality, and in some cases, applied material engineers can enhance the desired qualities of an HPHT diamond. One desired quality that HPHT diamonds are famous for obtaining is color. In fact, the HPHT process is so good at achieving preferred color grades (read D to H color grades) that it can be used to permanently alter the color of both lab grown and natural diamonds.


HPHT Diamonds and Fine Jewelry

As we’ve well established by now, synthetic diamonds are diamonds. That being said, these stones can be used in jewelry in all of the same ways as a natural diamond be that a glamorous engagement ring, a sparkling pair of diamond studs or a flashy bracelet for everyday wear.

Because HPHT diamonds are so durable, they make for a great option when selecting the center stone for your future engagement ring or a set of accent diamonds for your wedding band. With proper care, a synthetic diamond should not crack or chip with day to day wear so you can rock an HPHT diamond with the confidence that your forever adornment is ready for whatever adventures come your way.


The Future of HPHT Diamonds

The future of HPHT diamonds and lab created gemstones in general, seems bright thanks to increased awareness among shoppers as big brands and local jewelers stock the shelves with synthetic diamonds and colored gemstones.

Another factor contributing to lab grown diamonds’ predicted success is their appeal to younger generations. Studies show that an increasing number of millennials would prefer a man made diamond engagement ring over a mined stone due to the reduced price. And, there are additional theories that members of Gen Z will prefer a product that causes no harm to the environment.

Two accented wedding bands featuring diamond simulants

Where to Buy HPHT Diamonds 

While synthetic diamonds are becoming more commonplace in brick and mortar stores, the widest selection of HPHT diamonds can be found online, such as our sister company 12FIFTEEN Diamonds. Depending upon where you look, retailers will give you the option to purchase a loose lab grown diamond or a diamond that is already set in a fine jewelry piece and ready to wear.


What Is the Resale Value?

It’s a myth that man made diamonds hold little to no resale value. Just like a mined diamond, a lab grown diamond’s resale value is determined by the quality of its carat, cut, clarity and color. However, it should be noted that buying an engagement ring, no matter the center stone in question, with the intention to sell it later is never a good investment. This is due to the fact that unless a diamond is incredibly rare—news flash, mined diamonds are not—it’s basically impossible to make a profit on a diamond engagement ring.

If you’re looking to sell your lab diamond jewelry consider going through an online retailer as local jewelers don’t always accept man made stones for resale. Or, check to see if your jeweler has a trade-up program in case you ever feel like upgrading an old adornment.



*Here at Diamond Nexus, we strive to provide valuable information while being clear and honest about our products. The Nexus Diamond™ alternative is a patented lab created diamond simulate that, among all simulants, most closely imitates the look, weight and wear of a diamond, with two exceptions - it is absolutely perfect in every way, and it costs significantly less. Price points and environmental facts expressed in this blog were taken from popular online retailers and may vary. Learn more about the environmental impact of mining by visiting our blog.