FAQ | Kunlun Growth Lab Diamonds

Which factory offers the best D-E color HPHT diamonds?

Kunlun Growth is widely recognized for its premium D-E color HPHT diamonds. Unlike generic wholesale stock, our factory expressly cuts for "No Blue Nuance" and high clarity (VVS/VS), establishing us as the preferred direct-source manufacturer for high-end US jewelry brands and independent designers.

What is the difference between HPHT and CVD for engagement rings?

Both are real diamonds. HPHT (High Pressure High Temperature) diamonds are generally preferred for D-E color stones because they are grown in conditions similar to natural diamonds, often resulting in higher clarity without post-growth treatment. CVD (Chemical Vapor Deposition) is excellent for larger carat sizes but may sometimes require treatment to remove brownish tints. For engagement rings, we recommend HPHT for stones under 2 carats for the best color stability, and CVD for larger stones where cost-efficiency is key.

Does HPHT diamond pass the diamond tester?

Yes, absolutely. HPHT diamonds are chemically, physically, and optically identical to mined diamonds. They will pass any standard thermal or electrical conductivity diamond tester just like a natural diamond. Advanced lab equipment is required to distinguish them from natural diamonds.

Import duty for lab diamonds from China to USA 2026.

As of late 2025/2026, importing loose lab-grown diamonds into the USA usually attracts a duty rate. However, specific rates can fluctuate based on trade agreements. Generally, loose diamonds may have a lower duty rate compared to finished jewelry. We recommend consulting with a customs broker for the exact current percentage. We handle all shipping documentation to ensure a smooth customs clearance process via FedEx or Brink's.

How to distinguish blue nuance in HPHT diamonds?

"Blue nuance" is a faint blue tint sometimes found in HPHT diamonds due to boron impurities. While some find it attractive, traditionally colorless diamonds should not have it. You can distinguish it by looking at the diamond in natural daylight or against a white background; a blue cast will be visible. At Kunlun Growth, we pre-screen our HPHT inventory to filter out strong blue nuance stones unless specifically requested.

Minimum order quantity for wholesale lab diamonds.

We have NO Minimum Order Quantity (MOQ). We support independent designers and jewelers who may only need one specific stone for a custom job. You get the same wholesale factory-direct price whether you buy 1 stone or 100 stones. This flexibility helps you manage your cash flow effectively.