Introduction to NGTC Headquarters

National Gems & Jewelry Testing Co. Ltd.  (referred to as the “NGTC”) is :

Bureau-level business organization;

National-level laboratory;

National Jewelry And Jade Standardization Technical Committee (SAC/TC 298) Secretariat;

Ministry of Natural Resources Jewelry Jade Inspection and Evaluation Technology Innovation Center;

Jewelry Professional Skills Identification Guidance Center;

China Asset Assessment Association (Jewelry and Art) Professional Committee Secretariat.


Founded in Beijing in 1992, the NGTC currently employs more than 800 people, including 120 Ph.D.s and master degree holders, and has developed into a national jewelry jade science and technology culture integrated service platform with functions such as inspection and evaluation, scientific research and technology development, standardized construction, international exchange and cooperation, vocational education and skills identification, cultural industry leadership, and social public welfare services.


The NGTC is an authoritative institution for the testing of jewellery, jade and jewellery in China. It has laboratories in Beijing, Shenzhen, Shanghai, Guangzhou, Yunnan, Shenyang, Pingzhou, Xi'an, Zhuji, Suzhou, Hong Kong and other places. Undertake the supervision and spot inspection, arbitration inspection, commissioned inspection tasks of government departments such as market supervision, public security, justice, customs, etc., provide authoritative and fair professional service support for the government and society, and lead the technological and cultural innovation of China's jewelry industry toward high-quality development in the direction of "Digitalization, Intelligence, Branding & Internationalization".



NGTC Hong Kong


NGTC (HK) LTD. established in 2009, is a lab which has passed the accreditation of CNAS and it’s been designated for the diamond, gemstone and precious metal testing laboratory. The NGTC team has experts with master degree with CNAS approved signatories and internationally recognized professional qualifications gemologists.




In Hong Kong, there are no mandatory regulations requiring businesses to provide grading reports, therefore consumers can request grading report from the shop or ask for an issue of an independent and relevant appraisal body for the issuance of a professional grading report.


NGTC (HK) provides diamond and jewelry products for identification and grading service. The laboratory conducts “Diamond Authenticity” tests to make sure that the diamond is 100% natural and not synthetic; and then conducts the diamond grading process. Also, the diamond grading report number will be engraved on the diamond's girdle to avoid confusion. Consumers can check the grading results through the internet platform. This additional protection allows consumers to identify the specifics of the diamonds more clearly through the identification reports.

Co-operation Organizations

Gems and Jewelry Trade Association of China

The Gems and Jewelry Trade Association of China (GJT) was established in Beijing in 1991.  GJT aims to serve enterprises, develop the industry and standardize the industry for the purpose. In channelling industry policies, carry out industry self-discipline, promote brand development, promote jewelry industry.  GJT has produced fruitful work in strengthening international exchanges and cooperation, and for the continuous promotion of jewelry brands and the promotion of healthy development of industry norms laid the foundation for the accumulation of energy.




Diamond Federation of Hong Kong, China

The Diamond Federation of Hong Kong, China (DFHK) is a non-profit organization that aims to protect the integrity of diamonds and consumers’ interest by standardizing business practices. It is a joined force of two well-established associations in Hong Kong, namely the Diamond Importers Association (1959) and the Hong Kong Diamond Bourse (1985).


Since January 2000, DFHK has undertaken their missions in maintaining Hong Kong’s reputation as the diamond center in Asia and in promoting quality services and consumer rights. The NDQA, a consumer protection program was launched in 2015 to ensure an ethnical and professional image of our members.  It pledges to offer “Natural, Assurance & Protection” to consumers when purchasing diamonds. It takes pride in consolidating consumer rights and strives to exceed customers’ expectations.




Hong Kong Jewelry Manufacturers' Association (HKJMA)

The Hong Kong Jewelry Manufacturers' Association (HKJMA) was founded in 1988, and is dedicated to providing a diversity of quality services for our members and facilitating the development of the industry.




Hong Kong Jewellery & Jade Manufacturers Association

The Hong Kong Jewellery & Jade Manufactueres Association (HKJJA) was founded in 1965, and is the forerunner of export promotions for the jewellery and jade industry in Hong Kong. 




Hong Kong Jewellers’ and Goldsmiths’ Association

The Hong Kong Jewellers’ and Goldsmiths’ Association (HKJGA) was founded in 1953, represents jewelers engaging in jewellery trading, promotes the robust development of Hong Kong’s jewellery sector, and maintains the goodwill of their members.

Testing Standards

The People’s Republic of China National Standard (GB)
The China National Accreditation Service for Conformity Assessment (CNAS) assesses the technical capabilities of laboratories in accordance with the international standard ISO/IEC 17025 and issues accreditation qualifications for qualified laboratories. Accredited laboratories carry out the authenticity identification and quality grading of diamonds in accordance with the national standards "GB/T 16553 Identification of Jewelry and Jade" and "GB/T 16554 Diamond Grading" issued by the Standardization Administration of the People's Republic of China.


"GB/T 16553 Identification of Jewelry and Jade"

"GB/T 16554 Diamond Grading"



The laboratory will conduct the following tests on "Diamonds" :
1. Authenticity verification
2. Weight
3. Cut shape
4. Color Grading
5. Fluorescence reaction
6. Clarity classification
7. Symmetry and polishing classification
8. The ratio and cut grading of round diamonds



Other testing standards used :

"GB/T 16552 Name of Jewelry and Jade"

"GB/T 34543 Yellow Diamond Classification"

"GB 11887 Precious Metal Purity Regulations and Naming Method"

"GB/T 18043 Determination of Precious Metal Content-X-ray Fluorescence Spectrometry"

"GB/T18043-2019 Determination of Precious Metal Content"



National Standard for gem testing :

GB/T 32863-2016 Ruby ​​Classification

GB/T 32862-2016 Sapphire Classification

GB/T 34545-2017 Emerald classification

Testing Equipment

NGTC equipped with state-of-the-art testing equipments, including:


Laser Raman Spectrometer

Diamond Synth-Detect


GV5000 (Multi-band induced diamond luminescence)

DS5000 UV-Vis-NIR (Full-spectrum diamond screener)

X-ray Fluorescence Spectrometer

GEM3000 (Ultraviolet Visible Meter)



Prism Type Spectroscope


Chelsa Color Filter


Electronic Balance

Professional Gem Microscope



Except above professional equipments,

NGTC also equipped a series of reliable traceability standard samples with National Sample Certificate:

Diamond Master Stones (color D to N)

Diamond Fluorescence Master Stones

Yellow Diamond Master Stones

Precious Metal Samples

Standard Sample of White Gold Alloy

Standard Samples of Platinum Jewelry

Standard Samples of Platinum-Copper-Cobalt alloy

Standard Samples of Palladium-Palladium alloy jewelry

Standard Samples of Rose-colored alloy

Standard Samples of Jewelry Welding series composition analysis

Standard samples of Silver Jewelry

Munsell Sheets of Color


Expert Team

NGTC Experts

Lu Taijin

Ph.D & Chief Scientist

Dr. Lu Taijin is the Chief Scientist of National Gems & Jewelry Technology Administrative Center (National Gemstone Testing Center, NGTC). After graduating from the China University of Geosciences (Wuhan) in 1982, he received a doctorate in mineralogy from Tohoku University in Japan in 1989.  Prior to joining NGTC in 2009, he had 30 years of experience in gem research and identification, mineralogy, as well as materials science, with RIKEN, Japan, National University of Singapore, and Gemological Institute of America (GIA). He is the author of more than 200 gemological and other scientific articles, and an internationally known gemologist.

Yang Li Xin

Ph.D. (Mineralogy)

Dr. Yang is the Director of the Jewelry and Jade Standardization Technical Committee, responsible for the preparation and audit of national standards for tests related to diamonds and gemstones.


Dr. Yang has been engaged in vocational education and management and gem research and evaluation in the jewelry industry for more than 20 years. He has awarded the National Registered Jewelry Jade Quality Inspector (CGC), International Professional Qualification GIA G.G., FGA. In the construction and operation management of jewelry vocational training system, the construction of jewelry professional qualification standard system, jewelry identification appreciation and evaluation, jewelry brand culture and construction and other aspects of in-depth research, he has a wealth of practical experience, and has published a number of related works. Dr. Yang has long been a guest speaker at professional institutions such as the International Jewellery Federation, the International Colored Gemstones Association, and the Basel International Jewellery Show.

Song Zhonghua

Master (Gemology)

Song Zhonghua is the Senior Engineer, CGC.  After graduating from the China University of Geosciences (Beijing) and obtaining a Master’s Degree in mineralogy in 2001, Ms Song began her career in the National Gemstone Testing Center (NGTC) Beijing laboratory, and focused in the diamond grading and identification study area for more than 10 years. Ms. Song has a rich knowledge and deep understanding of  the origin and coloration, and treatment of diamonds both theoretically and practically. She is the author of more than 20 gemological articles and one book. She also participated in the editing of the national standards related to diamond identification. She is the senior specialist and leader of diamonds identification in NGTC group.  In 2017, she served as the Director of the Shenyang Laboratory of NGTC, and is currently the Deputy Director of the National Gems & Jewelry Technology Administrative Center (Beijing Laboratory).

NGTC (HK) Experts

Jiang TingJun

Deputy General Manager & Technical Director

CNAS Authorized Signatory.


Graduated from Guilin University of Technology and majoring in gemstones identification. He has worked as a gemologist and a technical trainer at the NGTC since 2014 and has extensive experience in diamond identification, colored gemstone identification, and diamond grading.


From July 2021, he has served as the Deputy General Manager and Technical Director of NGTC (HK).



Kong Dai

Senior Gemologist

Master Degree, graduated at China University of Geosciences (Beijing) - School of Gem Studies.


CNAS Authorized Signatory, experienced in diamond and gemstone testing.