Gem treatments explained — heat, oil, filling and diffusion

Most coloured gems on the open market have been treated. The practice is
ancient (Romans oiled emeralds) and legitimate — the dividing line is
DISCLOSURE.

• Heat — the great normaliser (sapphire, ruby, tanzanite, topaz...).
  Stable, permanent, accepted. Disclosed by default in honest trade.
• Oiling — emerald's cedarwood tradition; fills surface fissures.
  Accepted, discloseable, can need re-doing.
• Irradiation — creates/mostly creates blue topaz; stable.
• Glass-filling — fills cracks in low-grade ruby/sapphire with glass.
  Changes the stone's nature; price accordingly.
• Diffusion — colour added via chemistry at high heat; shallow (or
  deep in modern beryllium versions). Identification matters.
• Bleaching + polymer (jade B) — the unstable one; Type A jade is the
  safe buy (jade guide).

Telling heat from unheated, glass from corundum, B-jade from A — these are
bench skills from the identification course, previewed in the
free webinar replays.

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Go deeper — free

Watch the free replays at the gem webinar library — the gem e-book is the written companion. When curiosity becomes commitment, the gemmology foundation course is the ladder's first rung (online entry: GT100e); dates on the calendar. Play Name That Gem to train the eye between sessions.

What students say

“I hope to start and improve my own online shop.”

— Josephyn Y. (Singapore) · published student feedback

“It is fun, interesting & educational!”

— Shahirah A. (Singapore) · published student feedback

Free ways to explore

No sign-up, no payment — start with any of these.

WWatch a free gem webinarFREE
Full recorded sessions — the best free starting point.JJDMIS on YouTubeFREE
Course previews, blended-learning explainers and school life.FFree jewellery webinar replaysFREE
Recorded sessions on design and the jewellery industry.DDownload the gem e-bookFREE
The school's free guide to gems — pairs with the replays.

Keep exploring

Peridot — the green that comes from space and volcanoesPeridot explained — the olive gem from mantle and meteorites, its even colour, hardness anOnline jewellery courses — what you can genuinely learn remotelyWhich jewellery skills work as online courses — gemmology theory, design knowledge, busineThe 4Cs of diamonds — cut, colour, clarity and carat explainedThe 4Cs explained plainly — how cut, colour, clarity and carat actually drive diamond beauTopaz — the imperial and the blueTopaz explained — imperial and blue varieties, hardness vs cleavage, treatment norms and c

See the online and blended options

Gemmology can be started fully online, and every classroom course at JDMIS has a video-supported path.

Visit jdmis.edu.sg