Q&A: Everything You Wanted to Know about HPHT Treated Diamonds!

March 18, 2019

You're looking at a beautiful diamond and when notice that it is an HPHT treated diamond. Now you have questions. 

What are HPHT Diamonds?

An HTPHT diamond is a real, natural diamond that has undergone a High Pressure High Temperature process to enhance its color. The treatment turns a naturally brownish diamond into a whiter, more beautiful diamond. Because the diamond originally was brown, the treated diamond is still less expensive than if it were naturally found with such white color. The high pressure and 2300 degrees Celsius mimic the temperature at the Earth’s core and is a non-invasive, permanent process so that the beautiful results will last.


Do HPHT Diamonds Come with a GIA certificate?


Yes! The Gemological Institute of America—the most respected authority in diamond grading--recognizes HPHT diamonds, and considers the process non-invasive and permanent. Because there is no way to see if a diamond has been treated, it is important to have a diamond grading report from an independent lab like GIA. As part of its grading process, GIA tests all diamonds for treatments; if the diamond is treated, it will be disclosed on the certificate. At London Gold, we provide you with a GIA certificate so that you can buy with confidence.


Why Buy an HPHT Diamond?


People want to buy the biggest, best diamond at the best price. HPHT diamonds are a great option because they are natural diamonds, come GIA certified, and allow you to enjoy a bigger, more beautiful diamond at a fraction of the cost.


What is the Difference between an HPHT Diamond and a Non-HPHT Diamond?


Non-HPHT diamonds and HPHT diamonds are both real, natural diamonds. The difference is in the treatment. Because an HPHT diamond has been treated by extreme heat and pressure, its color has been enhanced and improved. You will be able to find non-HPHT diamonds with the same color as HPHT diamonds, but you’ll see a big difference in the cost!


How Can I Tell if a Diamond has been HPHT Treated?


Diamonds are emotionally symbolic, and you want to know if your diamond has been HPHT treated. Sellers are required to tell you if your diamond is HPHT treated so that you know what you are buying. Gemologists can detect HPHT diamonds using special detection equipment, and GIA includes any diamond treatment in its reports. Because there is no way to see if a diamond has been treated, it is important to have a diamond grading report from an independent lab like GIA.


Can All Diamonds be Treated with HPHT?


No. Less than 1% of all diamonds are suitable for HPHT treatment. In fact, HPHT treatment can only be used on diamonds with good clarity (typically, VVS2), because a diamond with inclusions can crack due to the extremely high pressure. This means your HPHT diamond was unique to begin with and born with impeccable clarity!




We encourage you to learn more about HPHT diamonds and see our stunning HPHT diamond collection at London Gold!

London Gold