Metals

The metal is the last decision in a ring and one of the most consequential. It sets the colour the diamond appears to carry, the way the piece wears across a lifetime, and the whole temperament of the thing. Two metals serve here — gold, in its several colours, and platinum.

Pure gold is too soft to hold a stone, so it is alloyed for strength, and the proportion of pure gold is marked in karats: 24kt is pure, 18kt is three-quarters gold, 14kt a little over half. Higher karats are richer in colour and more yielding; lower karats wear harder. The most common choices are 14kt, 18kt and 22kt.

White Gold

Gold alloyed with white metals and finished, traditionally, with a fine rhodium plating for a cool, bright surface. Its great virtue is that it keeps a diamond looking its whitest — there is no warm metal beside the stone to lend it colour — which makes it the natural companion to a near-colourless diamond. The rhodium finish is refreshed over the years to keep its brilliance crisp.

Yellow Gold

The classic, and the warmest. Higher-karat yellow gold — 18kt and 22kt — glows with a depth that lower alloys cannot match, and it flatters a stone that carries a little warmth of its own: a faint tint that might show against white metal settles happily into yellow gold. Soft underfoot at 22kt, it is best treated with a measure of care.

Rose Gold

Gold alloyed with copper, which lends it its blush. The more copper, the deeper and pinker the colour, and the harder the metal wears — rose gold is among the more durable of the golds. Its warmth is gentler than yellow’s and gives an antique, romantic cast; it suits warmer-toned diamonds and, against fair skin, reads as quietly distinctive.

Platinum

Naturally white, and worn pure or nearly so — no plating to refresh, the colour is the metal itself. Platinum is dense, holding a stone with real authority, and it does not wear away so much as redistribute, so over decades it gains a soft patina rather than losing substance. Like white gold, it keeps a diamond looking white; weightier in the hand and rarer than gold, it is the most enduring setting of all.