Buying Guide · 6 min read

How to read a diamond certificate without a loupe

Clarity, colour, cut and carat in plain language — and the two lines on the report that actually move the price.

A grading report is not a price tag. It is a description, and only two lines on it move the price much.

Cut is the one that shows

Colour and clarity are graded under a loupe by a trained eye. Cut is what you see across a room. An Excellent cut in a lower colour will out-sparkle a lazy cut two grades up.

Read the plot, not the summary

The clarity plot shows where inclusions sit. Under a prong, an SI1 reads as an VS. Dead centre under the table, it does not.

The two lines that matter

Check the report number is laser-inscribed on the girdle, and that the measurements match the stone in front of you. Everything else is negotiation.