Welcome to Diamond-Key Certificates

Confidence and trust are the foundation of any good supplier/client relationship. A certificate may significantly add to a diamond buyer's confidence level, but it shouldn't be considered a substitute for years of experience and expertise. Becuse it's only a summary of technical information, the certificate can't tell you if the diamond is a pretty stone. It may give you a good idea, but that's only the first step before actually seeing the stone.

The beauty of a diamond is subjective, to say the least, and that's the certificate's caveat. The certificate's limitation is in its objectivity. It is a diamond grading report, describing objective factors, both qualitative and quantitative; and an almost infinite combination of all of the variables, based on the 4 c's (cut, clarity, color, and carat), measurements, and physical properties, define each stone.

  • Cut is important because of a negative factor. If a stone's "cut" is not good (the proportions are off, the finish is not good, the girdle is too thick, or the facets are at incorrect angles) then the reflection of light will be affected.
  • Clarity is influenced by the number and type of inclusions, and if they interfere with the passage of light through the diamond.
  • Color preferences depend on individual markets. Fancy colors are valuable because of the rare supply. Some colors face-up white in yellow gold settings which is a practical decision when diamond jewelery manufacturers choose stones from a parcel.
  • Carat weigh is the deciding variable in diamonds (of more or less comparable quality) with reference to the price.
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    I've listed a selection of a few websites with good information about the 4c's, and also websites which give an explanation of how to read a certificate and what to look for. It's almost like a mini-on-line-diamond-course.

Explanation of the 4c's
  • www.mondera.com   This website's "Diamond Dictionary" explains certificate terminology: facets, culet, depth, fluorescence, length-to-width ratio, polish, symmetry, and the table. "The Whole Story" describes the progression of a stone from the mine through the polishing stages.
  • www.millenniumdiamond.com
  • www.diamondregistry.com
  • www.hwgem.com
  • www.jewelryzone.com
Explanation of the Certificate
  • www.diamondsource.com  This website's topic "How to Read a Diamond Certificate" covers clarity grade, shape and cut, measurements, weight, proportions, depth, table, girdle, culet, polish, symmetry, color grades, fluorescence, diagram, and comments. Questions can be e-mailed to: stevequick@diamondsource.com
  • www.henrymeyer.com   This website gives an interesting explanation of the the limitations of a diamond certificate, and asks "if the whole story is working" when it comes to a diamond. Also information about color and clarity influences on the diamond.
  • www.diamondguide.com
  • www.diamondring.com
  • www.colored-diamonds.com
  • www.jewelryexpert.com
  • www.jewelryjudge.com
  • www.niceice.com
  • www.diamondbrokersoffl.com
  • www.adfacet.com
  • www.tiffany.com
  • www.white-diamonds.com
Gemological Laboratories - Worldwide
  • AGS  www.ags.org
  • EGL  European Gemological Laboratory CLICK to access their site, www.egl.co.za  EGL is an interational network with gemological laboratories in Ramat Gan, Antwerp, London, Los Angeles, New York, Paris, Seoul. The lab offers certificates, mini-certs, and laser inscription on request; and grades for SI3 and has specialized specifications for Ideal, Excellent, Tolkowsy, and Premium cuts.
  • GGL  www.globalgemlab.com
  • HRD  www.diamonds.be
  • IDI  www.diamonds.org.il
  • GIA  www.gia.org  Carlsbad and Los Angeles, California; Kowloon, Hong Kong; Vicenza, Italy; Tokyo, Japan; Seoul, Korea; Moscow, Russia; Taipei, Taiwan; Bangkok, Thailand
  • GQI  Gem Quality Institute www.gqi.com
  • Harold Weinstein Ltd.  Gemology Lab  www.hwgem.com
  • Precious Stone Lab  www.precious-stonelab.co.uk
  • South Africa Diamond Certified Lab - Jewelry Council e-mail: lesmil@icon.co.za
  • Indian Diamond Institute Surat Tel:(91 26) 1 480809 Fax:(91 26) 1 481110
  • UGL   www.members.aol.com/ugline/U.G.L.html
  • United States Gem Lab   www.usgl.com
  • Zenhokyo Ltd. Tel:(972-3) 575-6036
Schools and Correspondence Courses
  • EGC  European Gemological College egc@netvision.net.il
  • EGL  European Gemological Laboratory  www.egl.co.za
  • Zenhokyo Ltd. Gemological Association of All Japan, Inc. Network Tokyo Tel: (03)3835-7484
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Revised: 14 May 01 1800 GMT