Gemological Science International (GSI) is the only major gemological organization established in the 21st century. Founded in 2005 in New York City, it has grown to become one of the largest gemological entities in the world with laboratory facilities spanning four continents.

Utilizing cutting-edge processes and proprietary technologies, along with a commitment to the highest ethical and responsible standards, GSI provides manufacturers and retailers globally with a wide range of grading reports and services for diamonds (both natural and lab-grown), colored gemstones, and jewelry. GSI is the leader in the testing and detection of undisclosed lab-grown diamonds in finished jewelry. The company also offers a variety of educational programs to the trade and has a dedicated internationally recognized team of researchers, scientists, and professionals committed to advancing gemological research in the industry.

Gemological Services

Diamond & Jewelry Grading Reports Diamond & Jewelry Grading Reports
GSI offers diamond and colored stone grading reports designed to meet your needs. All grading reports are available in a variety of formats.
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Research & Education Research & Education
GSI established its Research & Education Center to share important developments in the global gem and diamond industries, and further educate both the trade and consumers.
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Testing & Detection Testing & Detection
GSI’s leading screening and detection process ensures accurate results to meet the needs of transparency and disclosure.
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New York
  • Gemological Science International
    Schupstrat 9-11/B31 2018
  • Antwerp Belgium 32-0-3-689-1140
  • Gemological Science International
    AG-19-J, Silver Tower (AG Tower)
  • Cluster I Jumeirah Lake Towers
  • Dubai, UAE
  • Phone: 971-0-45573088
Hong Kong
  • Gemological Science International
    41 Man Yue St.
  • A3, 5th floor Hung Hom
  • Kowloon Hong Kong
  • Phone: 852-2-122-9378
Mumbai, India
  • Gemological Science International
    601-B, 6th Floor
  • Trade Center BKC
  • Bandra (East) Mumbai – 400051
  • Phone: 91 (022) 26540333
Surat, India
  • Gemological Science International
    Diamond World Building
  • Mini Bazar C-602, 6th Floor
  • Varachha Road Surat- 395006
  • Phone: 91 (261) 2550354
  • Gemological Science International
    Shimshon Building
  • Ste 9/13-15 Jabotinsky St 3 Ramat
  • Gan Israel
  • Phone: 972-0-3-752-3272

Digital Presence

GSI: Gemological Science International
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Jonathan Tack Joins GSI as Executive Vice President of Business Development

Jan 10, 2022 (New York, NY): Gemological Science International (GSI), one of the largest gemological organizations in the world and a global leader in diamond and jewelry certification, announced today that Jonathan Tack will join the organization as Executive Vice President of Business Development.

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