What does 18k gold plated actually mean?

Four terms get used almost interchangeably in online jewellery listings, and only one of them means solid gold. Knowing the difference is the single most useful thing you can learn before buying, because it determines what you pay and how long the piece keeps its colour.

Gold plated

A base metal — brass or stainless steel, usually — with a layer of gold bonded to the surface. "18k gold plated" describes the purity of that surface layer, not the amount of gold in the piece. Quality varies enormously with the thickness of the plating and whether it has been sealed.

Gold vermeil

Plating over sterling silver rather than base metal, with a legally defined minimum thickness in some markets. More expensive than ordinary plating, and a genuinely better base, though the gold layer still wears in the same way.

Gold filled

A thick layer of gold mechanically bonded to a base core — far more gold than plating, and correspondingly more durable and more costly. Uncommon outside the United States.

Solid gold

Gold all the way through, alloyed for strength. 18k is 75 per cent gold, 14k about 58 per cent, 9k about 37.5 per cent. It does not wear off because there is no layer to wear off. It is also many times the price.

So what is "18k gold tone"?

A description of colour, not content — the warm yellow that 18k gold happens to be. Any shop using that phrase, ours included, is telling you about the look of the finish. It is honest shorthand as long as nobody pretends it means solid gold, and you should treat a listing that blurs the two with suspicion.

Which should you buy?

For an engagement ring or something you intend to hand down, buy solid gold. For jewellery you want to wear every day and change with your wardrobe, good sealed plating gives you almost all of the look for a small fraction of the cost — and if you lose an earring on a night out, you will not lie awake about it.