Your
gemstones
unveiled

  • Asteriated luminescent structure in a rough diamond
    Asteriated luminescent structure in a rough diamond
  • Liquid film in a peridot from the Supat mine, Kohistan, Pakistan
    Liquid film in a peridot from the Supat mine, Kohistan, Pakistan
  • Rose Channels in a Sapphire in the Umba Valley, Tanzania
    Rose Channels in a Sapphire in the Umba Valley, Tanzania
  • Two-tone luminescent structure in a rough diamond
    Two-tone luminescent structure in a rough diamond
  • Structure of a pearl of Pinna nobilis
    Structure of a pearl of Pinna nobilis
  • Feldspath inclusions in a sapphire from Tirymena, Madagascar
    Feldspath inclusions in a sapphire from Tirymena, Madagascar

Your
gemstones
unveiled

Asteriated luminescent structure in a rough diamond

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Diamond services

We provide grading and analytical reports for both loose and mounted diamonds.

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Coloured gemstone services

With more than 20 years of expertise, we can guide you through the world of gemstones by uncovering authenticity, treatment, and geographical origin.

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Our exclusive services.

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GGTL laboratories

Welcome to GGTL Laboratories. An experienced laboratory like no other where science, technology, and research ally to give you the best of gemmology.

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Gemmology books
Insight

Gem books you absolutely need to read!

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Atelier de gemmologie à la Haute Ecole Arc - HES-SO : Retour sur un événement enrichissant
Insight

Gemology workshop at Haute Ecole Arc - HES-SO: A look back at an enriching event

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Natural glass inclusions in the form of atolls in an unheated ruby
Micrographs

Natural glass inclusions in the form of atolls in an unheated ruby

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