A diamond does not lose its sparkle. It loses its light to a thin film of hand cream, soap and skin oil on the pavilion — the underside of the stone, where light is meant to bounce back up to your eye. Clean the film away and the fire comes straight back.

The five-minute clean

1. Fill a small bowl with warm water and a few drops of mild washing-up liquid.
2. Soak the piece for a few minutes to loosen what has built up.
3. Brush gently with a soft, clean toothbrush — behind the stone and between the prongs, where most of the film sits.
4. Rinse under warm running water (plug the sink first).
5. Dry with a lint-free cloth and let it air-dry fully.

What to keep away from it

• Chlorine and harsh cleaners. Pool water, bleach and strong household products can weaken gold alloys over time.
• Hard knocks. A diamond is very hard, not unbreakable — take rings off for the gym, gardening and heavy lifting.
• Each other. Diamonds scratch other jewellery and other diamonds. Store each piece in its own pouch or compartment.

Ultrasonic cleaners

They work well on a solid diamond solitaire, but they are not right for every piece: coloured gemstones, treated stones and delicate pavé can loosen or be damaged. If a piece mixes diamonds with other gems, stay with the bowl and brush.

Once a year

Have the setting checked. Prongs wear slowly, and a loose stone gives little warning. Bring your piece to the atelier and we will look it over, tighten what needs it and give it a professional clean.