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Imperial Star Gems

Buying Guides

The four Cs guides explain the scales. These explain the decision — which specification to actually buy, given what the stone is for and who will wear it. Each one ends in a written specification you can send us, or take anywhere else.

Every report term, in the glossary

Engagement9 min read

Choosing an engagement ring stone

An engagement stone is the one diamond most people buy without ever having bought one before, and it is worn every day for decades. That combination — no experience, high stakes, hard wear — is what this guide is built around.

Read the guide

What every one of these assumes

Four principles sit underneath all six guides. If you read nothing else here, read these — they account for most of the difference between buying well and overpaying.

  1. 01

    Cut before everything

    It is the only grade that changes how much light comes back out of the stone. Nothing else compensates for a dull diamond.

  2. 02

    Grades are thresholds, not targets

    Clarity to eye-clean, colour to the setting metal. Past those points you are paying for a difference nobody will see.

  3. 03

    Millimetres, not carats

    Weight is not size. What a stone looks like on a hand is a measurement, and the report prints it.

  4. 04

    What a report cannot tell you

    Eye-clean, milkiness, bow-ties and make are not graded. For those, ask for a video — or ask us.

Or skip to the stones

If you already know the specification, the catalogues filter on every grade these guides discuss. If you do not, send us the brief — what it is for, what it is worth to you, and by when — and we will come back with stones rather than questions.

Send a brief