Each earring is a flat round disc of sterling silver hung from a latch back, with one straight line cut diagonally across its face. Two wedges of blue opal fan out from the top edge on either side of that line, split by a thread of silver, while the lower left and the right side stay bare and mirror-polished. The opal lies flush with the metal, with no prongs and no raised bezel, so the polished rim of the disc is its only frame. A circle crossed by a single line is the whole design of these silver disc earrings, set apart from opal drops in a teardrop or oval setting.

The stone is lab-created opal, grown in a laboratory rather than mined. Jewelers also call it synthetic opal, and it is not opalite, the opalescent glass sold under a similar name, because grown opal shows play of color the way mined opal does. In this pair the opal is deep blue, broken up by bright green flecks that flash and shift as the disc turns, so the earrings read blue-green at close range and blue from across a room. Sterling silver gemstone earrings usually hold a faceted stone in a setting; here the lab-created opal is shaped to fit and laid into the metal as an inlay.

A small ring joins the disc to the clasp, so the disc hangs free and swings with each turn of the head. That makes them opal dangle earrings, with nothing fixed stiffly under the lobe. From the front the clasp shows a smooth, pointed silver plate; behind it is the latch back, where the wire passes through the ear and clicks shut into a hinged loop, so there is no separate back to lose. The pair weighs 6 g, about 3 g per earring, which makes these lightweight earrings comfortable everyday earrings rather than a pair saved for evenings out.

Disc, ring and clasp are 925 sterling silver all the way through, real silver rather than a plated base metal, cast and then finished by hand in our workshop. A layer of rhodium over the silver keeps the surface bright next to the blue and helps it resist tarnish. The opal asks more care than the metal, so take the earrings off before swimming or cleaning, keep perfume and lotion away from the inlay, and store the pair in its own pouch.

The cut line, the bare silver and the strong blue suit plain clothes such as a white shirt, grey knitwear, navy or black. Round silver drop earrings are easy to find; a circle split by one straight line is the detail that catches the eye.