This minimalist promise ring draws the eye with the depth of its black onyx. The stone has a dense, matte black colour with none of glass's shine - the cabochon cut brings out this heavy, velvety opacity, and the stone's smooth dome sits calmly against the hand, free of unnecessary detail. The plain, narrow band doesn't distract from the stone - the whole form stays clean and contemporary. Onyx has long been linked to strength, endurance and confidence, and in this role - as a promise ring - those associations take on particular meaning.

We select each onyx for this design personally, examining the stone under light to find an intense, even black free of discolouration. Silver and good stones are getting more expensive, so a ring like this at a reasonable price is worth considering now. It is set in refined sterling silver 925 with a high-purity alloy - free of nickel and other additives that could irritate the skin. A rhodium layer protects the surface against tarnishing and scratches, keeping the metal's shine bright for years to come. On the inside of the piece you can see the maker's mark struck into it, registered with the French assay office - it attests to the origin of the metal.

This ring feels right for an evening out - with a little black dress, a silk blouse or a satin dress on thin straps, where the hand becomes the one place where a striking detail appears. The rest of your jewellery can stay in the drawer - a delicate chain at the neck is enough to keep the whole look from feeling overdone. Its very small size and weight of 1.8 g mean the ring sits lightly on the finger, almost unnoticeable, until a turn of the hand reveals the black of the onyx.