14ct vs 18ct: The Scratch Test You’ll Wish You Tried First

14ct vs 18ct: The Scratch Test You’ll Wish You Tried First

Choosing between 14ct and 18ct gold is as much about everyday wear as it is about look and resale. The most practical single check you can do at home or with a jeweler is a controlled scratch test. It helps you confirm composition, detect plating, and predict how the piece will wear. Below I explain what the scratch test tells you, how to do it safely, and how to interpret the results so you make the right choice for rings, bracelets, and everyday pieces.

Why metal hardness matters

Gold purity determines softness. Pure gold (24ct) is very soft. Alloys add harder metals (copper, silver, nickel, palladium) and increase strength. That means 14ct (marked 585) contains about 58.3% gold and more alloying metal. 18ct (marked 750) contains about 75% gold and is softer. In practice this means:

• 14ct resists dents and scratches better. Good for rings and everyday wear.
• 18ct has a richer, warmer color. It scratches and shows wear faster because it contains more soft gold.

Why it matters: harder alloys last longer in contact with rough surfaces. Softer gold polishes out scratches easily, but will also lose sharp edges on settings and profiles sooner.

What a scratch test actually tells you

A scratch test can check three things, when done carefully:

• Whether the surface is solid gold or just plated.
• An estimate of fineness (14ct vs 18ct) when combined with acid testing.
• How hard the alloy is — that predicts wear resistance.

It does not tell you the exact alloy recipe (e.g., percent copper vs palladium). Hardness and color both depend on the alloy mix, not just the karat. White gold plated with rhodium will look like white gold but scratch to a different color underneath.

Safe scratch test: touchstone + acid (practical and widely used)

This is the standard jeweler’s method. It removes only a tiny bit of metal and keeps the piece intact when done on an edge or inside a band.

What you need

• A black touchstone (hard, non-porous).
• Gold testing acids for 10ct, 14ct, 18ct (comes in labeled bottles).
• A steel scribe or needle to make a shallow streak.
• Protective gloves, goggles, and a ventilated space—acids are hazardous.

Step-by-step

• Choose an inconspicuous area: inside a ring band or the back of a pendant.
• Lightly drag the steel scribe so the metal leaves a thin streak on the touchstone. Do not gouge—make a shallow mark.
• Apply the 18ct acid to the streak. If the streak dissolves, it’s lower than 18ct. If it remains, move to the 14ct acid and repeat.
• If the streak resists 14ct acid, the metal is at or above 14ct. If it dissolves at 14ct but not at 10ct, it’s likely between those marks.

Why this works: the acid reacts differently with different gold contents. The test isolates a tiny sample, so the visible piece is not materially damaged. Still, practice or professional help is best if you’ve never used acids.

Quick non-destructive checks (use first)

Before you touch acids or scratch anything, do these safer checks:

• Hallmarks: look for 585 (14ct) or 750 (18ct) on the inside of rings and on clasp tags. Hallmarks are the fastest clue, but they can be faked.
• Visual color: 18ct yellow appears warmer and slightly richer. 14ct can be paler because of more alloy metal. This is subtle and depends on alloy mix.
• Rhodium plating check: rhodium plating is a thin coating (measured in microns). Light wear exposing a different-colored metal beneath signals plating. A jeweler can confirm with magnification.
• Magnet: not definitive, but a strong magnet attracting the piece suggests ferrous base metals (not gold). Gold is non-magnetic.
• XRF or electronic tester: non-destructive and accurate. Many jewelers offer this for a fee.

Interpreting scratch-test results

Outcomes you might see and what they mean:

• Streak resists 18ct acid: likely 18ct or higher. Expect softer metal and richer color.
• Streak resists 14ct but dissolves with 18ct acid: likely 14ct.
• Streak dissolves at all strengths: not gold or very low-fineness alloy.
• Surface scratches to reveal a different color: indicates plating. If yellow shows beneath white, the piece is yellow gold with rhodium plating. If base metal shows (grey/green), it’s gold-plated base metal.

Remember: some high-quality alloys (palladium white gold) behave differently to acids, so combine tests or consult an assay office for valuable pieces.

Practical buying and care advice

If the piece is for daily wear — engagement rings, wedding bands, bracelets — choose 14ct or look for hardening treatments. It wears better and often needs less maintenance. If you want the warm color and higher resale value, choose 18ct, but expect more frequent polishing and possible corner rounding over years.

If you are checking a secondhand purchase or inheritance, do the touchstone + acid test on an inside surface or let a jeweler perform an XRF assay. For plated items, ask about replating costs — rhodium replating for white gold is common and inexpensive relative to replacing the piece.

Finally, if you’re unsure or the item has high value, take it to a professional assay office or reputable jeweler. The scratch test is helpful, but done poorly it can damage a piece you want to keep intact.