The jewellery reference

What is it actually worth?

Free calculators for anything you own or are about to buy — and the one number the trade keeps to itself: what a diamond really fetches when you sell it.

Gold / gram today
27
Hallmarks decoded
37
Ring sizes, 5 systems
21
Gem types priced
$0
Cost, always
Calculators

Work it out yourself, at home

No appointment, no appraisal fee, nothing to post to a stranger.

Value my diamond & jewellery

Centre stone, side stones and the metal it is set in — priced as a whole piece. You get the retail figure a jeweller would charge and, far more usefully, the honest resale range you would actually be offered.

Start a valuation →

Ring sizer

Four ways to measure, including circles drawn true-to-life on your screen. Converts US, UK, Europe, India and Japan.

Find my size →

Measure it from a photo

No ruler, no scales, no certificate. Photograph your ring next to any bank card and get its true size in millimetres — then a ring size, a carat weight, or a metal value. Corrected for camera angle, and the photo never leaves your device.

Measure from a photo →

Gemstones & pearls

Ruby, sapphire, emerald, tanzanite and more — plus pearls. Treatment matters more than size here, and this shows you by how much.

Value a gemstone →

Budget calculator

Enter what you want to spend and see the biggest stone it buys — four ways, side by side, with what each one resells for.

See what it buys →

Gold & metal prices

Live spot prices per gram and what each karat is really worth as scrap. Refreshed every morning.

Today's prices →

Hallmark lookup

925, 750, 585, GF, EPNS — find out what the stamp inside your band means, and whether the piece has any metal value at all.

Decode a stamp →

Carat size chart

What a carat actually looks like. True millimetre sizes for every weight, drawn to scale on a real finger.

See the sizes →

My vault

Every piece you value, saved on your own device, with a running total of what the whole collection is worth as prices move.

Open my vault →
Why this exists

A diamond loses most of its value the moment you buy it

Every jeweller will tell you the retail price. Almost none will tell you what happens when you try to sell it back. On the secondary market a natural diamond typically recovers only a quarter to two fifths of what was paid for it — and lab-grown stones, whose prices have collapsed as production scaled, recover far less again.

That is not an argument against buying jewellery. It is an argument for knowing the number before you need it.

The data

Retail against real resale

Round brilliant, G colour, VS2, Very Good cut, GIA graded.

StoneTypical retailRealistic resaleYou keep

Estimates. Real offers vary with condition, certification, market timing and the buyer's own margin. Value your own piece for a figure matched to its specs.

Guess the Carat · daily

Train your eye

Streak 0

A new stone every day, drawn at its true face-up size on an average ring finger. Guess the carat weight, then see what it costs and what it actually resells for.

1.00carats — your guess
0.20 ct5.00 ct
Actual weight
ct
Retail price
Actual resale

Value my own diamond

Your record

Past stones

Missed a day? Every previous stone is still playable.

Know when your jewellery changes in value

Gold moves every day and diamond resale shifts with the market. Leave your email and we will tell you when it matters. Want a report right now? Value your piece — you can download it instantly, free.

Reference

Hundreds of worked pages behind the calculators — every ring size, every hallmark, every carat and shape.