HPHT Diamond Manufacturing
HPHT (High-Pressure High-Temperature) diamonds grow in hydraulic presses that replicate natural underground diamond conditions. Diamond seeds, graphite carbon and metallic flux are sealed in capsules, heated to 1300–1600°C under 5–7 GPa intense pressure for days. Carbon dissolves in melted flux and crystallizes gradually on seeds to generate rough stones. Most HPHT diamonds have minor metal inclusions and slight yellow tints caused by nitrogen elements.
In contrast, CVD lab diamonds are pure Type IIa diamonds nearly free of nitrogen. They present brighter white hues and vibrant fancy colors with fewer internal blemishes. CVD technology enables larger, cleaner gemstones without metal impurities, perfectly suited for premium jewelry. All CVD roughs and finished pieces can obtain authoritative IGI or GIA grading certificates for global jewelry retailers.