Parlour: art Deco emerald halo

What this ring is made of

Emerald

A rectangular step cut with long, straight facets. It flashes light in broad bands rather than sparkling, and it shows clarity clearly, so the quality of the stone matters more than with a brilliant cut.

Prongs

Small metal claws hold the stone from above. They let in the most light and show the most of the stone, and they should be checked by a jeweler every year or so.

Halo

A ring of small diamonds right around the center stone. It makes the center read larger and adds sparkle, but it also adds width and makes the head of the ring busier.

Cathedral shoulders

Arches rise from the band to cradle the stone, lifting it and framing it from the side. They add height, so check how the ring sits against a glove or a coat sleeve.

Milgrain

A row of tiny beads along the edges. It is the detail that makes a ring look antique, and it softens the line where metal meets stone.

Platinum

Platinum is naturally white, dense and hard-wearing, and it does not need replating. It costs more than white gold and picks up a soft, frosted patina over time that some people love and others polish away.