18K Gold Black South Sea Pearl Ring - 13mm Pearl & Diamonds - UK L

A 13mm black South Sea pearl ring in 18K gold with peacock iridescence

A 13mm black South Sea pearl ring in hallmarked 18K gold, for a milestone gift that stands apart from bridal white. Tilt the pearl and its surface moves through charcoal, sea green, bronze and violet, the peacock overtone that black-lipped oyster pearls are prized for. Six round brilliant diamonds, 2.5mm each and roughly 0.36 carats in total, sit in two heart-shaped mounts that lift the pearl clear of the finger. The ring weighs 7.13g and is a UK L (US 6, EU 51), with one available. Hallmarked 18K gold and gift-ready.

The setting knows to stay out of the way. Six round brilliant diamonds, 2.5mm each and roughly 0.36 carats together, sit three to a side in two small heart-shaped mounts that flank the pearl and lift it clear of the finger — a quiet piece of design you only catch from the side. The whole ring weighs 7.13 grams in hallmarked 18K gold with a bright white finish. Black pearls have long carried meanings of resilience, mystery and transformation rather than the innocence attached to white ones, which is what makes this a milestone piece rather than a bridal one. It is a UK L (US 6, EU 51), and there is one.

FAQs

1. What makes a black South Sea pearl different — and is the colour natural?
It comes from the black-lipped oyster, Pinctada margaritifera, farmed mainly around French Polynesia, and the dark body colour is produced by the oyster itself rather than added afterwards. What buyers pay for is the overtone: the green, bronze and violet that play across the surface as the light moves. Size compounds it — most black pearls fall between 8 and 12mm, so 13mm with clean symmetry is genuinely uncommon. More on how gems carry meaning across cultures is on our JewelMotif™ page.

2. What does the 18K hallmark mean?
18 karat means 750 parts pure gold per 1,000 — 75% gold, the standard for fine jewellery. (585 is 14k; 375 is 9k.) Solid gold does not tarnish and will not mark your skin, whatever its colour: yellow, white and rose gold differ only in the alloy metals mixed with the gold and the surface finish applied. Full detail is in what a UK gold hallmark really means.

3. Will UK L fit, and can it be resized?
UK L is US 6 and EU 51 — on the smaller side of average for a woman's ring finger, and worth measuring rather than estimating, because a 13mm pearl sits very differently on the hand from a plain band. Our UK ring size guide has a printable method and a full UK-to-US chart. We do not recommend resizing: the heat and pressure would put both the mounted pearl and the claw-set diamonds at risk.

4. Is a 13mm pearl practical to wear?
It is a statement ring, and it behaves like one — it sits high, so it will catch on knitwear and gloves. Pearls sit around 2.5–4.5 on the Mohs hardness scale, far softer than the diamonds beside them, so remove it for washing up, swimming, gardening and the gym, and store it apart from harder stones. Worn for evenings and occasions rather than daily labour, a pearl like this lasts generations.

5. Who is it for?
Black pearls suit a milestone rather than a beginning — a significant birthday, a promotion, a divorce, a decade survived. Where white pearls read as bridal, these read as earned, which is why they are so often bought by the wearer for herself. It arrives gift-ready in a JewelHub™ Luxe Ribbon Box; see JewelGift™ for how every order is presented, and JewelWhy™ for the cultural history behind pearls.

How to Style the Black South Sea Pearl Ring

Nothing competes with a 13mm pearl, so do not try: wear it alone, on the ring or middle finger, with bare or minimal other jewellery. If you pair anything, make it a plain white-metal band pushed to the opposite hand. The dark iridescence sits beautifully against black, charcoal and deep green, and turns unexpectedly modern with white. Explore the rest of the 14k & 18k Gold collection, or visit JewelBuild™ to see how one significant piece anchors a modular jewellery system.