Jewelry Glossary

Terms marked no definition are marketing words with no legal threshold, no certification and no technical meaning in the United States. They appear constantly in jewelry listings, which is why they are in this glossary at all.

316L stainless steel

The marine-grade stainless alloy, with added molybdenum for better resistance to salt and chlorine. A named grade is a checkable claim, unlike 'surgical steel'. It contains nickel, bound in the alloy. Read more

925

925 parts per thousand pure silver - 92.5% - which is the US legal threshold for calling something sterling silver. It describes the whole piece, not a coating. Read more

ASTM F136

The published specification for wrought Ti-6Al-4V ELI titanium alloy used in surgical implants. Also written G23 or Grade 23. Nickel-free by specification, which makes it the only genuinely checkable hypoallergenic claim in earrings. Read more

Bezel setting

A continuous metal rim that encircles a stone. The most secure common setting, with nothing to bend or catch, and the right choice for daily wear and for soft stones. Read more

Cubic zirconia (CZ)

A synthetic zirconium dioxide stone, Mohs 8 to 8.5. Bright when new, and it develops a surface haze after roughly two to five years of daily wear because household dust contains quartz at Mohs 7. Read more

Cultured pearl

A real pearl grown inside a real mollusc after a nucleus is deliberately introduced. Cultured is not the same as imitation - the pearl material is genuine nacre. Read more

Gold filled

A gold alloy layer mechanically bonded to a base-metal core, where the gold is at least 1/20 (5%) of the item's total metal weight. Roughly a hundred times the gold in minimum-spec plating, and it typically lasts 10 to 30 years. Read more

Gold plated

An electroplated gold coating of at least 10 karat and at least 0.175 microns thick. The karat figure describes the coating, not the item, which is usually brass. Read more

Gold vermeil

Gold of at least 10 karat, at a minimum thickness of 2.5 microns, over a sterling silver base. All three conditions are required. It is the only gold construction whose rule specifies the metal underneath. Read more

Heavy gold electroplate (HGE)

Gold electroplating at a minimum of 2.5 microns - about fourteen times the ordinary gold-plate minimum. A defined term, unlike vague phrases such as 'thick plating'. Read more

Hypoallergenicno definition

Nothing. There is no legal definition, threshold or certification for this word in US jewelry, and it appears freely on nickel-bearing metal. Look for a named standard such as ASTM F136 instead. Read more

Karat (K)

Gold content out of 24 parts. 24K is pure, 18K is 75%, 14K is 58.3%, 10K is 41.7% and is the US legal minimum for calling something gold. The remaining alloy sets hardness and color. Read more

Lab-grown diamond

A real diamond grown rather than mined - identical carbon, crystal structure and Mohs 10 hardness. The FTC permits calling it a diamond provided the lab origin is clearly disclosed. Read more

Micron

One millionth of a meter, the unit plating thickness is measured in. For scale, household aluminum foil is roughly 16 microns, and the minimum gold plating is 0.175. Read more

Millesimal mark

Purity expressed as parts per thousand: 585 is 14K gold, 750 is 18K, 925 is sterling silver. The European convention for the same information a karat mark carries. Read more

Mohs hardness

An ordinal scale of scratch resistance from 1 to 10. The critical threshold for jewelry is quartz at 7, because household dust contains it - stones below that abrade in ordinary wear. Read more

Moissanite

Silicon carbide, Mohs 9.25 - hard enough not to haze - with roughly 2.4 times a diamond's dispersion, so it throws noticeably more colored fire. A distinct mineral, not a diamond simulant. Read more

Nacre

The layered calcium carbonate and organic material that makes up a pearl and gives it lustre. Porous and soft, and damaged permanently by perfume, hairspray and cleaning dips. Read more

Niobium

An elemental metal used in jewelry for sensitive skin. Because it is an element rather than an alloy, there is no nickel in it by composition rather than by grade. Read more

Non-tarnishno definition

A marketing claim with no threshold behind it. The useful version is a named base metal - stainless steel and titanium genuinely do not tarnish, and gold does not either. Read more

Prong setting

Metal claws gripping a stone at points. The most popular setting and the least secure - prongs bend and wear, and they are the overwhelming reason stones get lost. Read more

PVD

Physical vapor deposition - a coating process that produces a harder, better-bonded layer than electroplating. It describes how the coating got there, not how much gold is in it. Read more

Rhodium plating

A thin platinum-group metal coating, used on white gold to achieve the bright white finish people expect. It wears and needs redoing, typically every one to three years on a ring. Read more

Rolled gold plate (RGP)

A bonded gold layer at 1/40 of total weight - half the gold of gold-filled, and a legally distinct term. Better than electroplating, less than gold-filled. Read more

Sterling silver

At least 925 parts per thousand pure silver, with the remainder usually copper. Solid metal throughout, and the copper is what causes tarnish. Read more

Surgical steelno definition

An unregulated phrase with no defined composition. It usually means 316L but is not required to, and it does not imply nickel-free. Look for the grade instead. Read more

Tarnish

A surface reaction between a metal and airborne compounds - most often sulfur reacting with the copper in sterling silver. It is a film, not damage, and it polishes off. Read more

Titanium steelno definition

Not titanium. This is stainless steel with a misleading name, and it contains nickel. If nickel-free is why you are buying, this is the phrase to walk away from. Read more

Waterproof jewelryno definition

Usually gold-colored plating over stainless steel. True about the base metal, which is unaffected by water, and misleading about the coating, which still wears in one to three years. Read more

White sapphire

Colourless corundum, Mohs 9 - harder than cubic zirconia and roughly the same price. Lower refractive index, so it looks softer and glassier rather than bright. Read more

The pattern worth noticing

Read the list and a shape emerges. The terms with legal thresholds behind them - gold-filled, vermeil, 925, ASTM F136, 316L - all describe something specific and measurable. The terms with nothing behind them - hypoallergenic, surgical steel, non-tarnish - all describe a feeling about a product.

That is the single most useful thing on this site. How to read a jewelry listing turns it into a six-step checklist you can apply to anything.