18K and 24K gold: what is the difference

The numbers 18K and 24K tell you how much of a piece is pure gold. Divide the karat number by 24 and you have the answer.

Gold content

• 24K gold is practically pure. In Vietnam it is called 9999 gold, meaning 99.99% gold.
• 18K gold is 18 parts gold out of 24, or 75% gold. The hallmark stamped on the piece reads 750.
• The remaining 25% of 18K gold is an alloy of silver, copper, zinc or palladium. The alloy decides whether the metal turns out yellow, rose or white.

Common units: 1 chỉ equals 3.75 grams, and 1 lượng equals 10 chỉ, or 37.5 grams.

Hardness and durability

Pure gold is soft. A plain 24K band worn every day picks up fine scratches and small dents; that is the nature of the metal, not a flaw. 18K gold is harder thanks to its alloy, so it holds prongs firmly and keeps fine details crisp.

That is why every Kim Bảo Minh Châu diamond piece is crafted in 18K gold or 950 platinum, while the Everyday Gold and Fortune & Prosperity collections use 24K gold for plain, solid shapes with few sharp details.

Colour

• 24K gold is a deep, warm yellow.
• 18K yellow gold is slightly paler.
• 18K rose gold carries more copper in its alloy.
• 18K white gold uses a white alloy and is usually plated with rhodium for an even shine. The plating wears over time; bring the piece back to re-plate when warm tones start to show.

Which to choose

• Engagement rings and stone-set jewellery: 18K gold or platinum.
• Everyday pieces, traditional wedding gifts, torques and plain bands: 24K gold.
• Saving in gold: 24K gold, bought back close to the day's gold price.

Every price on the website is built from metal weight, stone value and craftsmanship, and follows the price board approved for the day.