Craft · Chapter 19

Precious metals: 10k, 14k, 18k gold vs. platinum

Purity, density, color, wear patterns, and skin sensitivity compared for long-term wear.

A diamond sits in metal that must withstand decades of friction, pressure, skin chemistry, and minor impact. Knowing how gold karats and platinum alloys behave over time helps match the mounting to both the design and the wearer’s routine.

Karat is a measure of pure gold content

Pure gold (24k) is too soft for fine stone setting. Karat indicates parts of pure gold out of 24: 18k is 75% pure gold (marked 750), 14k is 58.3% (marked 585), and 10k is 41.7% (marked 417). The remaining proportion consists of alloy metals—such as copper, silver, zinc, and nickel or palladium—which add hardness and adjust color.

18k gold: richer color, softer surface

At 75% gold, 18k yellow gold has a deeper, warmer color and feels heavier than lower karats. In comparable alloys it is generally softer than 14k and may show fine surface scratches sooner, although alloy choice and finishing also matter. Its higher gold content makes it less prone to tarnish than lower karats. 18k white gold usually retains a faint warm tint and is commonly rhodium plated for a whiter surface.

14k gold: a common middle ground

At 58.3% gold, 14k is typically harder than 18k and costs less than 18k or platinum, while keeping a clear gold color. It is widely used for engagement rings in the United States. Greater hardness helps resist scratches and deformation, but the security of fine prongs and pavé still depends on design, metal thickness, and workmanship more than on karat alone.

10k gold: harder, paler, more alloy

At 41.7% gold, 10k is generally the hardest and least expensive of the three, and it is the lowest fineness that may be sold as karat gold in the United States. Its yellow is paler than higher karats, and its larger share of alloy metals makes tarnish or discoloration from sweat and household chemicals more likely. Some white 10k alloys contain nickel, which matters for wearers with nickel sensitivity.

Platinum: dense, white, and slow to wear

Jewelry platinum is typically 90% or 95% pure, often marked 900 Plat or 950 Plat (Pt950). It is naturally white and considerably denser than gold—roughly 60% heavier than 14k gold for the same volume. It does not need rhodium plating and rarely causes skin reactions. When platinum is scratched, much of the metal is displaced rather than removed, producing a soft satin patina. It still wears gradually over the years, and its prongs still need periodic inspection and, eventually, retipping.

Worth remembering: Platinum tends to displace rather than lose metal when scratched, but no metal is maintenance-free.

Yellow, rose, and white gold

Yellow gold is typically alloyed with silver and copper. Rose gold uses a higher proportion of copper for its pink tone. White gold combines gold with whitening metals such as nickel or palladium and is usually finished with rhodium plating. That plating wears with use and is often renewed every one to three years, depending on wear. Platinum and yellow or rose gold do not rely on a plated surface, although every metal changes in finish as it is worn.

Skin sensitivity

Nickel is one of the most common causes of allergic contact dermatitis, and some white gold alloys contain it. Wearers with a known metal sensitivity can ask for nickel-free options such as palladium white gold, platinum, or higher-karat yellow gold. Because gold and platinum alloys vary, confirm the exact alloy with the maker.

Worth remembering: Choose metal for its long-term physical behavior on the finger, not just its initial appearance in the display case.

Essential language

Karat: A unit measuring the purity of gold, with 24 karats representing pure elemental gold.
Alloy: A mixture of two or more metals engineered to improve strength, hardness, or color.
Patina: A soft, satiny sheen that develops on platinum with wear as scratches displace metal across the surface.
Rhodium plating: A very thin electroplated layer of rhodium applied over white gold to give a brighter, cooler white surface.
Hallmark: A stamp indicating metal fineness, such as 750 for 18k, 585 for 14k, or Pt950 for platinum. In some countries an independent assay office applies it; elsewhere a maker’s quality mark serves a similar role.

Questions to take with you

Does the wearer have sensitive skin or a known nickel allergy?
Is routine rhodium replating for white gold acceptable, or is naturally white platinum preferred?
Does the setting use fine prongs or pavé, and is the chosen metal thick enough for that construction?
How does the weight of platinum compare with the lighter feel of gold on the hand?
Is the satin patina of worn platinum preferred, or the high polish gold can be restored to?