Yellow Gold

Yellow gold in jewelry is always a mixture. Pure gold, 24k, is soft enough to mark with a fingernail, so it is melted with copper and silver to make it wearable. Karat states the gold share out of 24. An 18k piece is 75 percent gold and stamped 750, and 14k is 58.5 percent and stamped 585. At 10k the share is 41.7 percent, stamped 417, the lowest that may legally be called gold in the US.

Hardness runs opposite to purity. More alloy metal means a stiffer surface. So 14k holds a polish longer under daily knocks while 18k scratches sooner and repays you with a deeper, warmer color. Rings and bracelets absorb almost all the abuse a jewelry box ever sees, so 14k earns its place there. Earrings and pendants rarely touch anything and lose nothing in 18k.

Gold does not tarnish or corrode, so the color cannot wear off and the metal keeps its value as material. A jeweler can size, solder and repolish it indefinitely, which is what makes a solid gold piece worth repairing decades later. You pay for exactly that. The metal is priced by weight, so the same design costs several times its plated twin. Every repolish removes a little thickness, thinning a ring shank over a lifetime.

Gold is mined as ore or recovered from recycled jewelry and electronics, then refined to 99.9 percent purity, which the trade calls 24k. That pure metal is melted with measured amounts of copper and silver to hit a karat. The recipe also sets the exact shade: more copper reads warmer, more silver reads paler.

The alloy is either cast or stamped. Casting pours it into a mold made from a wax model, which is the lost wax casting method behind most jewelry. Stamping starts from metal rolled into sheet and wire. After casting, the piece is filed, sanded and polished through progressively finer abrasives. The karat mark is stamped or laser marked somewhere discreet, usually inside a ring shank or on a chain's clasp tag, often beside a maker's mark. Look for that stamp before paying a solid gold price.