Why 925 sterling silver.

What the number means

92.5 per cent pure silver, 7.5 per cent other metals, almost always copper. That is the complete definition of sterling. It is a millesimal fineness standard, not a brand, not a grade, and not a marketing term.

Pure silver at 99.9 per cent is too soft to make jewellery from. It bends under ordinary handling, and it cannot hold a stone: a prong of fine silver would open on its own within weeks. The 7.5 per cent copper is what gives sterling the stiffness a setting needs to actually work.

So "925 sterling silver" tells you the alloy is correct. It does not tell you the piece is well made. Those are separate questions, and only one of them is answered by a stamp.

Why we use it rather than gold

Our stones are cool: white, grey, blue, violet. Moonstone, labradorite, aquamarine, lapis lazuli, amethyst. Yellow gold fights all five, and it wins, which is the problem.

Silver finished in rhodium is slightly whiter and cooler than raw silver. Set behind a pale blue or grey stone it recedes and lets the stone be the subject. That is the entire job of a setting.

What rhodium plating does, and its honest limits

Rhodium is a platinum-group metal, applied over sterling in a very thin layer. It does three useful things: it is harder than silver, so the surface resists scratching; it does not react with sulphur, so tarnish slows dramatically; and it is cooler in tone, which suits our stones.

It also wears. On a ring worn daily, expect the high points to start showing warmer silver underneath somewhere between one and three years in, depending entirely on how you use your hands. Earrings and pendants, which touch almost nothing, can go a decade. Replating is a routine and inexpensive job at any competent jeweller.

Anyone describing a plated finish as permanent is either not paying attention or hoping you are not.

Tarnish, explained properly

Tarnish is a chemical reaction, not damage. The copper in the alloy reacts with sulphur compounds in the air and forms silver sulphide, which is the dark film you see. It is a surface layer a few molecules thick. It is not rust and it is not eating the metal.

What speeds it up: humidity, so silver tarnishes faster in a monsoon; sulphur in polluted air; perfume, hairspray, sunscreen and chlorinated water; some cosmetics; and the natural chemistry of your own skin, which genuinely varies from person to person.

What slows it down: wearing it. Skin contact keeps silver bright, and jewellery left in a drawer tarnishes faster than jewellery worn daily. This surprises almost everybody. Beyond that: dry storage, a closed pouch, and rhodium plating.

Cleaning, in about a minute

For light tarnish, which is nearly every case:

1. Warm water with a drop of mild washing-up liquid
2. A soft toothbrush around the setting, gently
3. Rinse, then dry completely with a soft cloth
4. Finish with an impregnated silver polishing cloth

What not to do, and why:

• No ultrasonic cleaner. Fine for a plain band, potentially destructive for moonstone, labradorite, lapis or any stone with internal fractures. The vibration propagates existing fractures.
• No steam cleaner, for the same reason plus thermal shock.
• No dip-style chemical tarnish removers on plated finishes or porous stones. They strip rhodium and can attack lapis and turquoise.
• No toothpaste. It is an abrasive. It will scratch a polished surface and dull a rhodium finish. This advice circulates endlessly online and it is simply wrong.
• For lapis lazuli specifically, at 5 to 6 on the Mohs scale and porous, do not soak it at all. A barely damp cloth, dried immediately.

How to tell sterling from plated base metal

The stamp. Genuine sterling is marked 925, sometimes STER or STG, usually inside a band or on the back of a setting. Its absence proves little, since very small pieces are hard to stamp. Its presence is meaningful.

Hallmarking. In India, BIS hallmarking for silver independently certifies fineness. Where a piece carries it, that is verifiable rather than claimed. Drishtal's hallmarking status: 925 sterling silver, rhodium finished.

A magnet. Silver is not magnetic. If a piece is attracted to a magnet, the core is ferrous and it is plated. This only catches the worst offenders.

Tarnish pattern. Sterling tarnishes evenly. Plated base metal wears through at edges and high points, exposing a different colour underneath. Two colours means plated.

What to realistically expect

If you buy sterling silver intending to wear it for years:

• It stays bright with regular wear
• It darkens in a drawer, and a cloth fixes that in a minute
• Plating on a daily-wear ring eventually wears at the high points, and replating is straightforward
• It will scratch. So does platinum, and so does gold.

A piece worn for a decade should look like it has been worn for a decade. A stone can be kept perfect. A metal in daily contact with skin cannot, and it should not have to be.

Read the full care guide for storage and per-stone specifics.