Global Gemology - Rare Gems & Jewels
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synthetic diamonds


Synthetic diamonds are becoming increasingly more popular amongst a certain percentage of consumers.

Below is more information on lab created diamonds.

hpht (high pressure high temperature)



​​
Virtually all synthetic diamonds are grown using HPHT (high pressure, high temperature) techniques.

Can be colorless to near colorless, or a very light gray, green or blue caused by faint internal growth zoning due to the presence of impurities.

Elongated or rounded, metallic flux inclusions.

It's possible the diamond will be attracted to a rare earth magnet due to the presence of flux inclusions.


Will often have unevenly-distributed fluorescence.

Usually inert under LW.  Weak to moderate green, yellow, blue or orange under SW.

​Will commonly phosphoresce for over 60 seconds.
​

CVD (chemical vapor deposition)



​​
A small percentage of synthetic diamonds are grown using a CVD (chemical vapor deposition) technique.  
​
Near colorless, faint to dark brown or gray, or even light to dark blue due to the presence of impurities.
 
Brownish material can be treated to colorless.
 
Polished diamonds are usually shallow, due to being cut from tabular crystals.
Often inclusion free.
 
Inert or weak orange to yellow orange under LW fluorescence.  Weak to moderate orange to yellow orange to SW.  No phosphorescence.
 
CVD diamonds will require advanced gemological testing.
Diamond crucible
Photo courtesy of Seki Diamond
Synthetic diamond crucibles
Photo courtesy of Hoobly Classifieds
  • HOME
  • ABOUT
  • SHOP
  • SERVICES
    • APPRAISALS
    • EXPERT WITNESS TESTIMONY
    • SELL YOUR JEWELRY
  • GEMOLOGY
    • GEM ENCYCLOPEDIA
    • THE ART OF GEMOLOGY
  • JEWELRY EDUCATION
    • DIAMOND FACTS
    • JEWELER DIRECTORY
    • JEWELRY PERIODS
    • POCKET WATCHES
    • NATIVE AMERICAN JEWELRY
  • GLOSSARY