20 August 2026 · Jeff Jewellery
How to Read a Diamond Certificate Like a Gemologist
GIA, IGI, HRD — what the grades really mean, and the details that move the price.
A diamond certificate is the stone's passport. Learning to read it protects your investment.
The Four Cs — In Order of Impact
Cut quality determines brilliance more than any other factor; never compromise below Excellent or Very Good. Colour and clarity follow — but remember that differences invisible to the naked eye can move the price by thousands.
Fluorescence and Finish
Strong fluorescence can make some stones appear hazy — while faint fluorescence in lower colours can even help. Polish and symmetry grades complete the picture.
The Jeff Jewellery Standard
Every certified stone we present is verified against its certificate under the loupe, in front of you. Ask us to show you — transparency is the house policy.