Since 1980

    Guild Gem Lab, based in Los Angeles, CA, USA, was established by the renowned American gemologist Mr. Charles Carmona in 1980. Guild owns rich experience, refined database and solid research in areas of gemstone identification, grading and geographic origin determination. Guild now can be found in Los Angeles, Hong Kong and Shenzhen.

    Color Grading

    Since 1980, Guild has been focusing on testing colored gemstones, especially  on treatment detection, origin determination and color grading of emeralds, rubies, sapphires and more.


    The principle of Guild Gem Laboratories is to “provide clients with professional and trustworthy services”, to ensure the integrity, trust as well as accuracy of gem testing.

    Highly Efficient

    By applying highly efficient work procedures and ensuring the premium quality of testing, it normally takes 7 workdays to finish the job, which save much valuable time for our customers, compared with the general testing duration of 1-2 months elsewhere.

    • Guild is Coming! Who?

      Read More
    • 一张高品质证书的自我修养

      Read More
    • 颜值与才华齐飞:Guild高级证书详解

      Read More
    guildlabs guild