Why Doesn't Gold Tarnish? The Chemistry of a Noble Metal

Gold does not tarnish because it is a noble metal: its atoms hold on to their electrons so tightly that oxygen, water and most acids cannot react with it under everyday conditions. Solid gold jewelry can still dull slightly, but that comes from the other metals in the alloy, or from lotion and grime on the surface, not from the gold itself. For anyone wearing gold through humid salt air in Palm Beach, here is the chemistry, and what it means for care.

What does tarnish actually mean?

Tarnish is a thin layer of a new compound that forms when a metal reacts with something in its environment. Silver reacts with sulfur compounds in the air and turns dark as silver sulfide forms on the surface. Copper reacts with oxygen and moisture and eventually turns green. Iron rusts. In each case, atoms at the surface give away electrons to oxygen or sulfur and become part of a new, duller material.

Gold is the famous exception. Pure gold left in air, in seawater or buried in the ground for thousands of years comes out looking like gold. That is why gold objects from ancient tombs, such as the treasures of Tutankhamun, still shine.

Why is gold so unreactive?

Chemists measure how willingly a metal gives up electrons. Gold sits at the far noble end of that scale, with one of the highest standard reduction potentials of any metal. In simple terms, gold strongly prefers to stay as a neutral metal atom rather than become an ion, so ordinary oxidizers in air and water cannot pull its electrons away.

There is a beautiful piece of physics behind this. Gold has a heavy nucleus with 79 protons, and its innermost electrons move at a significant fraction of the speed of light. Einstein's relativity makes those fast electrons behave as if they were heavier, which pulls the outer 6s orbital closer to the nucleus. That outer electron is held more tightly and is harder to give away. The same relativistic shift changes how gold absorbs light: it absorbs some blue light and reflects the rest, which is why gold looks yellow instead of silvery like most metals.

Gold is not completely inert. It dissolves in aqua regia, a mixture of hydrochloric and nitric acids, and in cyanide solutions used in mining. Those reactions are part of how gold is refined, which we explain in How Is Gold Refined? The Chemistry That Turns Old Gold Into 24K.

So why can a gold ring look dull?

Almost all fine jewelry is an alloy, because pure 24K gold is very soft. 18K gold is 75% gold, stamped 750, and 14K is 58.3% gold, stamped 585. The rest is usually silver, copper and other metals that add strength and change the color. Those partner metals are not noble, so they can react a little at the surface, especially in lower karats.

• Higher karat, more resistance. 18K gold is three quarters gold, so it keeps its color more easily than 14K.
• Film, not corrosion. Most dullness on solid gold is a film of skin oils, sunscreen and soap that scatters light. It washes off.
• Chlorine is the real enemy. Strong chlorine in pools, hot tubs and bleach can attack the alloy metals over time and weaken the piece, so jewelers advise taking gold off before swimming.

Our guides to gold alloys and karat stamps go deeper into what is inside each karat.

What does salt air do to gold jewelry?

Salt air near the ocean carries moisture and chloride. For solid gold, this is mostly harmless: the gold will not rust or turn green. What you may notice is a light film that makes polished gold look less bright, and salt crystals that collect in tiny gaps around stones. A wave shaped piece like the Wavy Diamond Bracelet, handmade in 18K recycled gold with ethically sourced natural diamonds, keeps its color through sun and sea air; a gentle wash now and then brings back the shine.

The Wavy Diamond Heart Bangle is made from 17 g of 18K gold with 1.05 ct total of ethically sourced natural diamonds, including a central heart diamond of approximately 0.65 ct. That much solid gold will look the same in twenty years as it does today, with a little care.

How do you clean gold so it shines again?

• Soak for a few minutes in warm water with a few drops of mild dish soap.
• Brush gently with a very soft toothbrush, especially behind the stones.
• Rinse in clean water and dry with a lint free cloth.
• Avoid bleach, chlorine and abrasive powders.

Our step by step guide, How to clean gold and diamond jewelry at home, covers stones and settings in detail.

Does textured gold behave differently?

Chemically, no. A raw texture scatters light in many directions, so a light film is less visible than on a mirror polish. The Raw Diamond Ring, cast in 14K gold with an organic raw texture and an approximately 0.31 ct natural diamond, is a good example: it is designed to look real rather than flawless, so everyday wear only adds to its character.

Margaret Krinetz Fine Jewelry, handmade in Tel Aviv and shipped to Palm Beach, works in solid 14K and 18K gold for exactly this reason. Every piece is handmade to order, and if you have a question about metals or care, write to the studio.

Frequently asked questions

Can I wear solid gold in the ocean?
Seawater will not tarnish solid gold, but waves can loosen a clasp and sand can scratch. Taking jewelry off before swimming is the safest habit.

Does 14K gold tarnish?
It can show a slight surface change over time because it contains more alloy metals than 18K. Regular gentle cleaning keeps it bright.

How long does delivery to Palm Beach take?
Every piece is handmade to order in 4 to 6 weeks, then ships by DHL Express in 3 to 5 business days, with free shipping on orders over $1,500.