White gold is an alloy, not a different metal
Pure gold is always yellow. To make it white, refiners alloy it with white-coloured metals — historically nickel, increasingly palladium, plus silver, zinc and sometimes manganese. These metals dilute and mask the yellow. The result is a pale, slightly grey-gold colour — not the mirror-white most people picture, which is why the final step is usually a plating layer.
What white gold is made of, by karat
Karat measures pure gold content and does not change with colour. 18k white gold is 75% pure gold and 25% alloy metals; 14k is 58.5% pure gold and 41.5% alloy; 10k is 41.7% gold. The remaining percentage is where the "white" comes from — a nickel-based mix is harder and cheaper, a palladium-based mix is naturally whiter, costlier and safe for nickel-allergic wearers. A 14k white gold ring and a 14k yellow gold ring hold the identical amount of gold; only the other 41.5% differs.
Rhodium plating — the real source of the bright white
Most white gold jewelry is finished with rhodium, a rare, very hard, bright-white platinum-group metal, applied as a coating a fraction of a micron thick. Rhodium is what gives new white gold its brilliant, slightly cool shine. It wears off gradually — typically over 12 to 24 months of regular wear on a ring, longer on earrings or pendants — revealing the warmer, greyish tone of the alloy beneath. A jeweller can re-polish and re-plate for a modest fee, and many owners do it every year or two. Palladium white gold can be worn un-plated because the alloy itself is acceptably white.
White gold vs platinum vs silver
Platinum is denser, more durable, naturally white all the way through (no plating), hypoallergenic and more expensive — it develops a matte patina rather than staying mirror-bright. Sterling silver is far cheaper and whiter than un-plated white gold but soft, tarnish-prone and not ideal for holding stones long-term. White gold sits in between: harder than pure gold, lighter and cheaper than platinum, but reliant on rhodium plating to look its best. Nickel-based white gold can trigger contact dermatitis in nickel-sensitive wearers; palladium-based white gold and platinum do not.
What white gold is worth
For melt or scrap value, white gold is priced exactly like yellow gold of the same karat — on its pure gold content at the live spot price. Rhodium plating and the alloy colour add nothing recoverable. The white gold scrap value page runs that calculation, and the 14k and 18k per-gram pages show the current rate. To confirm a piece is solid white gold rather than rhodium-plated silver or base metal, check the karat hallmark and see how to tell if gold is real.