Antique Jewelry Care & Hallmark Guide

Antique jewelry survives for a century or more when it's read correctly and handled gently. This guide covers how to identify what you have from the marks stamped inside it, and how to care for it so it lasts another hundred years.

Reading Hallmarks ✦ Care by Material ✦ Storage & Wearing

Reading Hallmarks

A hallmark is a small stamp, usually hidden inside a ring's shank or on the reverse of a pin or pendant, that tells you what a piece is made of. Not every antique carries one — hand-made pieces and older work sometimes went unmarked, and that alone isn't a red flag. When a mark is present, here's what it usually means.

PLAT / PLATINUM

Solid platinum, typically 90–95% pure. The standard mark on Edwardian and Art Deco fine jewelry.

900PT / 950PT

Platinum purity expressed per thousand — 900 parts platinum per 1,000, or 950 per 1,000. Common on European and modern platinum pieces.

10% IRID PLAT

Platinum alloyed with 10% iridium for added strength — a common American mark from the early 1900s through the 1930s.

10K / 14K / 18K / 22K

Gold purity expressed in karats out of 24. 14K and 18K are the most common on antique American and European pieces.

375 / 585 / 750 / 916

Gold purity expressed as parts per thousand — the metric equivalent of a karat stamp, common on European pieces. 375 = 9K, 585 = 14K, 750 = 18K, 916 = 22K.

STERLING / 925

Sterling silver, 92.5% pure. Often found on Georgian and Victorian pieces, or as the "silver top" layer over gold in 18th- and 19th-century settings.

Maker's Mark

A small stamped symbol, initials, or name identifying the workshop or jeweler that made the piece — distinct from a purity mark, and the basis for a signed piece.

British Assay Marks

UK pieces often carry a small set of symbols rather than a single stamp — a purity mark, an assay office symbol (a leopard's head for London, an anchor for Birmingham), and a letter indicating the year of assay.

Care by Material

Antique settings are more delicate than new ones — decades of wear thin the metal and loosen prongs and foil work that were never meant to be disturbed. A few rules by material go a long way.

Platinum & Gold

Clean with mild soap, warm water, and a soft brush. Avoid ultrasonic and steam cleaners on antique pieces — the vibration can loosen old prongs, foiling, or filigree that a new piece wouldn't have.

Pearls

Wipe with a soft, dry cloth after wearing — perspiration and perfume slowly dull the nacre. Never use ultrasonic cleaning, harsh chemicals, or submerge for long periods. Have pearls restrung periodically if worn often; the silk cord wears before the pearls do.

Opals

Opals contain water and can crack from sudden temperature changes or prolonged dryness. Avoid ultrasonic cleaners, steam, and harsh heat — a soft damp cloth is usually all they need.

Enamel Work

Including guilloché and pliqué-à-jour. Wipe gently with a soft cloth only — avoid chemical cleaners, ultrasonic devices, and sudden temperature changes, which can crack or lift antique enamel.

Foil-Backed Stones

Common in Georgian jewelry. Never submerge in water or clean with liquid — moisture can reach the foil backing behind the stone and cause it to tarnish or lift, dulling the sparkle it was designed to create.

Filigree

Clean with a very soft brush and gentle pressure only. The pierced wirework that defines filigree is also its most fragile feature, and can bend or catch under too much force.

Diamonds & Hard Gemstones

Sapphires, rubies, and diamonds can generally tolerate mild soap and a soft brush. Still avoid ultrasonic cleaning on antique settings specifically — the stone may be hard enough, but a century-old mounting may not be.

Storage & Wearing

Store Separately

Keep pieces in individual soft pouches or a lined box. Diamonds and hard stones can scratch softer metals and gems if left touching in a drawer or jewelry box.

Mind the Light

Pearls, coral, and some organic materials can fade or dry out with prolonged direct sunlight. Store away from a sunny windowsill.

Last On, First Off

A good habit for pearls and soft stones especially — put jewelry on after applying perfume, lotion, and hairspray, and take it off before showering, swimming, or sleeping.

When in Doubt, Ask

If you're not sure how to clean or store a specific piece, we're always glad to advise — every piece we sell has already been through our own care process, so we know exactly what it needs.