January 2025 | Lab Grown Magazine

January 2025 | The Lab Grown Diamond Resource Book 20 Mailed to 24,000 Jewelers Monthly - To advertise call (888) 832-1109 | January 2025 21 LGD How HPHT & CVD Could Be Yesterday’s Tech BY DAN SCOTT ADVANCEMENT Part 2 of 2 India has overtaken China with its vast investment and factories featuring rows of CVD machines occupying the space. Unlike HPHT, CVD machines are small- er, and some varieties can be interconnected to share or redistribute energy consumption. Photo: Anjali Diamonds Pvt Ltd The typical growth morphology and rough photo illustration of Natural Dia- mond, HPHT and CVD processes respectively Image: GIA Education n Part one of this story, we outlined some strong advancement within the LGD growth sector. Now, this closing section speaks to HPHT and CVD comparisons and offers a drilldown on a technology, which may replace either of the staple growths if it becomes more affordable. In discussions with highly respected professionals close to this LGD growth specifics, none go on record but agree on a few facts. First, the need for higher technology trained personnel, larger spaces, and the need for more energy consumption surround HPHT with metal artifacts in the final growth cycle being a major disadvantage. To properly review such, we offer unbiased comparisons for you to formulate your own opinion. Here’s a summary and comparison of CVD to HPHT production in categories of industry interest. Color Distribution CVD diamonds tend to have a more even color distribution and tend to offer higher levels of clarity than HPHT diamonds. In the past, HPHT diamonds were prone to developing yellowish color, due to the presence of nitrogen, but the technique has grown and developed over the years eliminating such. Fluorescence  HPHT and CVD diamonds show higher incidences of fluorescence, a type of glow seen in ultraviolet light. Fluorescence is often misinterpreted as a negative, but doesn’t have any effect to the appearance of a diamond (unless under UV or backlight). Its presence is noted during grading, but its existence (or lack of) doesn’t affect the grade. HPHT diamonds tend to have higher instances of fluorescence than diamonds formed with the CVD method, but both have been noted. Graining HPHT diamonds show graining patterns based on their growth structure. CVD diamonds have no growth patterns.  Growth Processes & Time While Natural Diamonds growth morphology is an octahedron shape with growth in eight directions, HPHT creates a cuboctahedron shape with growth in fourteen directions. The CVD process produces a cube shape and growth is only in one direction – up. The growth rate for HPHT diamonds is faster than CVD with HTHP producing