Solid Gold vs Gold Plated vs Vermeil vs Gold Filled: The Science of Gold Layers

Solid gold is a gold alloy all the way through, so there is no layer to wear off; gold plated, vermeil and gold filled jewelry carry a thin skin of gold over a different metal underneath. For a reader in Miami, where jewelry meets sunscreen, salt water and humidity every day, the thickness of that skin is the whole story. Here is the science, with the official US definitions behind each word.

What does "solid gold" actually mean?

Pure gold is 24 karat, and it is too soft for most jewelry. So goldsmiths mix it with other metals such as silver, copper and zinc to make an alloy. 18K means 18 parts gold out of 24, or 75 percent; 14K means 14 parts out of 24, about 58.5 percent. That is why European style hallmarks read 750 and 585. If you want the full chemistry of how those other metals change color and hardness, read our post on gold alloys and the chemistry of yellow, rose and white gold.

"Solid" simply means the alloy is the same through the entire piece. Scratch it, polish it, resize it, and you are still looking at the same 18K or 14K gold underneath.

Every piece we make is solid gold. The Wavy Diamond Heart Bangle, for example, is 18K gold through and through, which is why the wave keeps its color after years of wear.

How thin is gold plating?

Gold plating is usually done by electroplating: the base metal sits in a solution of gold ions, an electric current runs through it, and gold atoms deposit on the surface. The US Federal Trade Commission Jewelry Guides (16 CFR Part 23) set the bar for calling something "gold electroplate": the gold or gold alloy must be at least 10 karat and at least 0.175 microns thick, roughly 7 millionths of an inch.

To put that in perspective, a micron is a thousandth of a millimeter. A layer of 0.175 microns is far thinner than a human hair. Friction from a desk, a bag strap or sand slowly polishes it away, and the base metal starts to show.

What is vermeil?

Vermeil (pronounced ver may) is a specific, regulated term in the US. According to the same FTC Guides, vermeil must have a base of sterling silver, coated with gold or gold alloy of at least 10 karat, with a minimum thickness of 2.5 microns of fine gold, about 100 millionths of an inch. The FTC uses the same 2.5 micron figure for "heavy gold electroplate".

So vermeil carries a much thicker gold layer than basic plating, over a precious metal. But it is still a layer. Under it is silver, which can tarnish when it is exposed.

What does "gold filled" mean?

Gold filled is not filled with gold. It is a base metal with a thick sheet of gold alloy bonded to the surface by heat and pressure, a mechanical process rather than electroplating. The FTC Guides allow the term "gold filled" only when that gold layer, of at least 10 karat, makes up at least 1/20 of the total metal weight. At 1/40 of the weight, the piece may be called "rolled gold plate" instead. You will often see stamps like "14/20 GF", which means 14K gold making up 1/20 of the weight.

Why does the layer matter so much in Miami?

Three things wear gold layers down: abrasion, chemistry and time. Beach sand is abrasive. Chlorine in pools, salt in sea water and some ingredients in sunscreen and fragrance are chemically active. Humidity keeps moisture on the skin. A thin plated layer simply has less material to lose before the metal underneath appears.

Gold itself is famously unreactive, which is why it does not tarnish; we explain that in why gold does not tarnish. In a solid gold alloy, that stability runs through the entire piece rather than sitting on the surface.

That is also why bands meant to be worn every day, like our 3mm Gold Wedding Band in 14K solid gold, are made solid. A ring touches everything you touch.

Quick comparison: how do the four compare?

• Solid gold: gold alloy throughout, marked by karat (14K, 18K). Can be polished, resized and repaired.
• Gold electroplate: at least 10K gold, at least 0.175 microns, over another metal.
• Vermeil: sterling silver base, at least 10K gold, at least 2.5 microns.
• Gold filled: at least 10K gold layer bonded mechanically, at least 1/20 of the metal weight.

How can you tell what you are buying?

Read the stamp and the product description. A solid gold piece is marked with its karat or fineness, such as 14K, 18K, 585 or 750. Plated pieces in the US should name the karat of the plating together with words like "GEP" or "plated", and gold filled pieces are often marked GF. Our explainer on karat stamps and hallmarks walks through the marks.

What I love about solid gold is that it lets a piece become part of your life story. The Wavy Diamond Ring started as a sine wave in my notebook; in 18K recycled gold it can ride every wave of your year, beach days included. Margaret Krinetz Fine Jewelry, handmade in Tel Aviv and shipped to Miami, makes every piece to order in 4 to 6 weeks.

Curious whether a piece you own is solid or plated? Send me a photo of the stamp through the contact page and I will tell you what it means.

Frequently asked questions

Can I swim in solid gold jewelry?
Solid gold does not tarnish, but chlorine and salt can dull the surface and loosen dirt around stones, so rinse and dry your jewelry after the pool or the beach.

Is vermeil real gold?
Yes, the outer layer is real gold of at least 10 karat and 2.5 microns, but the core is sterling silver, so it is not solid gold.

How long does delivery to Miami take?
Each piece is handmade to order in 4 to 6 weeks, then DHL Express delivers to Miami in 3 to 5 business days, free on orders over $1,500.