What 24k, 22k, 21k and 18k mean

Karat marks describe how much of a piece is gold and how much is another metal. The scale runs up to pure gold, so a higher mark means a softer, more yellow metal, and a lower mark means a harder alloy that holds its shape in daily wear. The page shows metal value worked out from the world gold price, not a shop quote, so treat it as a guide to the raw material rather than a retail offer.

What each karat means in practice

Pure gold is the top of the scale. It is dense, deeply yellow and very soft, so it dents and scratches easily and is rarely used for rings or chains that get knocked about. It suits pendants, earrings and display pieces, and it is the form investors usually hold.

The next mark down is the traditional choice for South African jewellery. It keeps most of the gold content while adding enough alloy to survive everyday wear, which is why it dominates wedding bands, bracelets and traditional pieces. It is still fairly soft, so settings need care.

A slightly lower mark gives a harder metal with a warm colour. It is common in bangles and heavier chains where stiffness matters more than maximum gold content.

The lowest common jewellery mark is the workhorse alloy. It is noticeably harder and paler, and it takes stones and fine settings well. Much of the fashion and gem-set jewellery sold locally uses it, often in white or rose tones depending on the alloy metals.

Alloy metals and colour

Copper deepens the colour and adds hardness. Silver and zinc lighten it. Palladium or nickel in the mix produces white gold, which is usually plated to brighten the surface. The alloy recipe, not just the karat, decides how a piece looks and wears.

Hallmark stamps

Look inside the band or on the clasp for a stamped mark. South African pieces often carry a karat stamp plus a maker's mark, and imported goods may show a different convention. A stamp is a declaration by the maker, not a guarantee, and worn or faked marks exist.

Testing a piece at home and beyond

• Check the stamp first, then weigh the item and compare its heft with its size; gold feels heavier than it looks.
• Use a magnet: gold is not magnetic, so a strong pull suggests another metal underneath.
• Rub gently on unglazed ceramic; a gold streak is a good sign, though plated items can mislead.
• Ask a jeweller or assay office for a proper test when value matters, especially for inherited or high-carat pieces.

Remember that the figures on this page come from the world metal price and describe melt value alone. Craftsmanship, stones and retail margins sit outside that calculation.