Jewellery Education Cobalt

Made from a highly durable alloy, cobalt is four times harder than platinum while at the same time, less dense. Because of its natural hardness, cobalt jewellery is extremely scratch, chip and corrosion-resistant. Its lower density and natural malleability allow for strong, dynamic designs with less weight. Cobalt is also hypoallergenic, making it an ideal choice for those with sensitive skin or an active lifestyle.

At Blue Nile, we offer two finishes: a rich blackened colour as well as a natural, lustrous white, both of which will hold a lifelong polish. Similar to platinum in colour, cobalt does not require rhodium plating and does not tarnish.

Care and Polishing While scratch-resistant, all metal will show a natural wear pattern with time. If scratched, your cobalt jewellery can be reconditioned, a complimentary service provided by Blue Nile.

Shop our cobalt jewellery collection.

Diamond Size


  • Hypoallergenic
  • Shatterproof
  • Scratch-resistant