0.31 ct Radiant Halo Ring, G IF GIA

0.31 carats, radiant cut, GIA certified G colour and IF clarity, surrounded by 0.09 carat of D–F VS brilliants in 18K white gold. Report 6501831150.

IF means Internally Flawless: at ten-power magnification a trained grader finds no inclusions inside the stone at all. There is one grade above it, Flawless, which additionally requires no surface blemishes and is rare enough that most jewellers go years without handling one. In practical terms IF is the top of the clarity scale.

It is worth saying what that does and does not buy. Visually, at this size, nothing that VS2 would not also give you — the eye stopped being able to adjudicate several grades earlier. What it buys is the certificate, and the position that certificate holds in every appraisal and pricing grid the trade uses. That is a real asset; it is simply not an optical one.

The radiant cut is the other half of this ring. It is a cut-cornered rectangle with brilliant-style faceting: the outline of an emerald cut, the light behaviour of a round. Radiants also hold colour a little more than round brilliants do, which is why a G here reads slightly warmer than a G would in a round — and why the halo is set in D–F, to hold the contrast at the edge.

Round centre with a halo instead: 0.30 ct G SI2.