The 4Cs of diamonds — cut, colour, clarity and carat explained

The 4Cs grade every diamond. Understanding their WEIGHTING is the actual skill:

• Cut — the only C entirely created by human hands, and the biggest driver of SPARKLE. A well-cut lower colour diamond outshines a poorly-cut flawless one. Prioritise this.
• Colour — graded D (colourless) to Z. The eye notices the top steps only in large stones; in a well-cut stone, G-I reads white to most people.
• Clarity — Flawless to Included. Most inclusions are invisible without 10x loupe; eye-clean beats letter-chasing.
• Carat — weight, not size (cut controls spread). Prices jump at magic weights (1.00ct) — a 0.9ct well-cut stone can look bigger than a poorly cut 1.0ct.

The buyer's rule: cut first, then colour/clarity to eye-clean, then carat to budget. Grading reports (GIA and peers) describe the stone — they do not guarantee beauty, cut does.

Diamonds sit inside the gemmology foundation course's syllabus alongside coloured stones — the trade treats them as one knowledge system.

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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 intend to contribute articles to jewellery magazines and hope that someday I can be an authority in this field. That's a dream.”

— Yen Ting C. (Singapore) · published student feedback

“I love all subjects, especially metalsmithing. I just love to fire and shape things.”

— Angie K. (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, busineTopaz — the imperial and the blueTopaz explained — imperial and blue varieties, hardness vs cleavage, treatment norms and cWatch the gem webinars — the free replay libraryThe free gem webinar replay library explained — what the recorded sessions cover, how to w

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