There are several methods you may use to verify the authenticity of a diamond:

Select a merchant that provides a diamond grading report for every diamond purchased

GIA Grading Reports will clearly list the grade and weight of the diamond. Certificates of 1 carat or more will generally be accompanied by a drawing of the diamond itself and a map of its inclusions. A magnifying glass can be used to compare the GIA number and inclusions on the diamond with the information on the certificate to determine the authenticity of the diamond. GIA also uploads the certificate of each identified diamond to its official website. The customer only needs to enter the GIA number to determine the authenticity of the certificate.

Use a diamond tester

Thermal conductivity refers to the ability of materials to directly conduct thermal energy. Due to the high thermal conductivity of diamonds, the use of a diamond thermal conductivity tester is a fast and accurate method. It can instantly test diamonds of various sizes and shapes. When the instrument is in direct contact with the diamond surface, it will immediately mark it as true and false. The new tester pen can easily distinguish the most similar diamond simulant Moissanite.

In addition, the Gemological Institute of America (GIA) has set up a laboratory in Hong Kong where customers can review or check their GIA Diamond Certificates as well as verify the authenticity of the GIA Diamond Certificates they receive and of the diamonds they purchase. This protects the interests of customers and gives them confidence. Please note that the services apply only to unmounted diamonds and take approximately two weeks. The service typically costs a few hundred Hong Kong dollars and payment is settled directly with GIA. For more details of services and fees, please visit https://www.gia.edu/doc/Diamond_DZ__FeeSchedule_Q1_2025_HKD.pdf.

There are also many seemingly simple and quick ways to verify the authenticity of diamonds. Some of these, however, are not recommended, such as refraction test (the diamond is placed face down on white paper with black lines), fog test (lightly sigh on the surface of the diamond) and hardness test (light stroke on the surface of the diamond with a pen). As these methods are neither precise nor accurate, their results are not credible, and we do not recommend these tests.