Bench terminal

Bench tools

Ring sizes across US, UK, EU and millimetres, the reader strength opticians start from at your age, and how to clean and store each metal, stone and lens.

Ring size converter

US, UK, EU and millimetres from one number. Measure the inside of a ring that fits with a ruler (diameter), or a strip of paper around the finger at the knuckle (circumference).

US / Canada	7
UK / Australia	N½
EU / ISO (circumference)	54.3 mm
Inside diameter	17.3 mm

Fingers swell in heat and in the evening and shrink in cold; measure at the end of a normal day. Wide bands (6 mm+) fit tighter than thin ones: go up a half size.

Reader strength by age

The starting band opticians print on the rack. It is a starting point for off-the-shelf readers, not a prescription: if one eye differs from the other, or distance vision is also blurred, that is an eye exam.

+1.00 to +1.50

Test: hold a book at 14–16 inches; the right strength makes it sharp there, and a stronger one forces you to hold it closer. Sun readers are the same strength with a tinted UV-rated lens. Readers by strength →

How to clean it

By material, from what jewelers and the GIA publish. When in doubt, soap, water and a soft cloth are safe for everything except pearls and soft stones.

Clean

Warm water, a drop of dish soap, a soft cloth; a silver polishing cloth for tarnish.

Avoid

Chlorine (pools, bleach), sulfur (hot springs, eggs, rubber bands), perfume and lotion put on after the piece.

Store

In an airtight bag with an anti-tarnish strip; silver tarnishes in air, faster in humid air.

The materials glossary says what each metal, plating and stone actually is.