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Diamond education · Knowledge hub

Everything worth knowing before you buy a diamond.

Plain-language guides, reference tables and a full glossary, from a team with more than 30 years in the Australian diamond industry. Balanced advice on natural and lab-grown, so you can compare with confidence.

Written by the CTJ Jewellery team, led by founder Greg Ward

Start here

Buying a diamond in five steps.

  1. 01

    Set your priorities

    Size, quality, origin or budget. Decide which matters most before you look at a single grade.

  2. 02

    Choose natural or lab-grown

    Both are real diamonds. Natural is valued for rarity. Lab-grown gives you more size or quality for the budget.

  3. 03

    Pick a shape and setting

    Shape is personal taste. The setting decides how the diamond is held, protected and seen.

  4. 04

    Balance the four Cs

    Cut first, then colour and clarity you can’t see past, then carat to suit your hand and budget.

  5. 05

    Compare real diamonds

    Grading reports describe a diamond. Only seeing diamonds side by side shows which looks best.

How to buy a diamond

The guides

Eight in-depth guides, grouped by where you are in the process.

Diamond basics

  • Guide 01 · 5 min read

    Natural and lab-grown

    • Both natural and lab-grown are real diamonds with the same properties.
    • The difference is origin: billions of years in the earth, or weeks in a laboratory.
    • Only laboratory equipment can tell them apart.
    Natural and lab-grown diamonds
  • Guide 02 · 8 min read

    The four Cs

    • Cut has the biggest effect on how a diamond looks.
    • Colour is graded D to Z, clarity FL to I3.
    • Carat is weight, not size. One carat is 0.2 grams.
    The 4Cs of diamonds
  • Guide 03 · 6 min read

    Diamond shapes

    • Round brilliant is the most brilliant shape.
    • Oval, pear and marquise look larger for their weight.
    • Step cuts such as emerald and asscher show clarity.
    Diamond shapes

Choosing well

  • Guide 05 · 5 min read

    Settings and metals

    • Bezel settings protect the diamond most.
    • Hidden halo and cathedral settings add sparkle and height.
    • White metals show colour, yellow and rose gold warm it.
    Settings and metals
  • Guide 04 · 4 min read

    Grading reports

    • GIA and IGI are independent, internationally recognised laboratories.
    • Reports record measurements, grades and origin.
    • Two diamonds with the same report can look very different.
    Diamond grading reports

Buying with confidence

After you buy

  • Guide 08 · 5 min read

    Care and warranty

    • Warm water, mild soap and a soft brush.
    • Professional inspection at least once every 12 months.
    • Manufacturer’s warranty, in addition to Australian Consumer Law.
    Care, warranty and repairs

Natural diamonds

A seven-part series on natural diamonds.

Buying questions

Direct answers to the comparisons people ask about most.

Reference library

Quick answers and tables to keep open while you compare.

Ready to see diamonds

Book a complimentary consultation, or send us a brief.

Request a quote