1. The Physics of CVD vs HPHT Synthesis
While both CVD and HPHT result in real chemical diamonds, their growth environments produce distinct crystal structures and chemical characteristics.
- CVD (Chemical Vapor Deposition): Methane and hydrogen gases are ionized by microwave plasma inside a vacuum reactor. Carbon atoms deposit onto a diamond seed plate layer by atomic layer.
- HPHT (High Pressure High Temperature): Uses massive hydraulic presses (Bult-Type, Cubic, or Belt) to exert over 60,000 atmospheres of pressure at 1500°C on carbon and metal catalyst solvents (iron/nickel).
2. Why Type IIa CVD Is Preferred for Fine Jewelry
Type IIa diamonds represent less than 1.8% of natural diamonds and are virtually free of nitrogen impurities. CVD growth natively yields Type IIa purity, producing icy-white brilliance and high optical transparency.
Wholesale Advantage: CVD diamonds eliminate the risk of metallic flux inclusions and magnetic anomalies commonly found in HPHT stones.