What is it actually worth?
Free tools for anything you own or are about to buy — with the number the trade keeps to itself: what a diamond really fetches when you sell it.
Value what you own
Retail, and the honest resale figure.
Value my diamond & jewelry
Center stone, side stones and the metal, priced as a whole piece — the retail figure a jeweler would charge and the resale range you would actually be offered.
Start a valuation →Value it from a GIA report
Your report states what the diamond is and never what it is worth. Enter the grades for retail and resale — plus which of them are quietly costing you.
Read my report →Gemstones & pearls
Ruby, sapphire, emerald, tanzanite and more. Treatment matters more than size, and this shows you by how much.
Value a gemstone →Gold & metal prices
Live spot per gram, every karat, and what a scrap buyer will really offer.
Today's prices →Scrap gold & offer checker
Melt value in grams, pennyweight or troy ounces — what each kind of buyer pays, and whether the offer in front of you is fair.
Check an offer →Class ring value
Half of all class rings are base metal under a trade name. Check the stamp, weigh it, and see the real melt figure before anyone makes an offer.
Check my ring →Hallmark lookup
925, 750, 585, GF, EPNS — what the stamp inside the band means, and whether there is any metal value.
Decode a stamp →My vault
Every piece you value, saved on your own device, with a running total as prices move.
Open my vault →Buy the right stone
Before the counter, not after.
What my budget buys
Enter what you want to spend and see the biggest stone it buys — four ways, side by side, with resale.
See what it buys →Compare two diamonds
Two specs side by side: true size, price, resale, price per carat, and which is the better buy.
Compare →Lab-grown vs natural
The same stone both ways — what each costs today, and what each is worth in five years.
See both →How much to spend on a ring
There is no rule. What your income actually supports, and what that money buys.
Work it out →Diamond price per carat
Why a 1 carat stone costs far more than two half carats — the whole curve, with the cliffs.
See the chart →Diamond color chart
D to K on the same 1 carat stone: what you can see, and what each step costs.
See the scale →Diamond clarity chart
FL to I1: what is visible to the eye, what needs a loupe, and the price of each grade.
See the grades →Measure it
No ruler, no scales, no appointment.
Ring sizer
Four ways to measure, including circles drawn true to life on your screen, calibrated against any bank card.
Find my size →Measure from a photo
Photograph your ring beside a bank card and get its true size in millimeters — corrected for camera angle.
Measure from a photo →Carat size chart
What a carat actually looks like: true millimeter sizes for every weight and shape, drawn on a finger.
See the sizes →Reference
The answers people look up most.
Birthstones by month
Every month's stone, what it is worth, and the honest alternative when the classic is out of reach.
See all twelve →Jewelry insurance cost
What cover should cost for a piece of your value, and when it is not worth insuring at all.
Estimate it →Diamond sizes & prices
Every carat weight in every shape — 110 pages of size, price by grade, and resale.
Browse →Ring size charts
Every size in US, UK, EU, India and Japan with diameter and circumference.
All sizes →Hallmarks explained
All 27 marks: metal, purity, and whether the piece is worth anything by weight.
All marks →Free widgets for your site
Ring sizer, diamond size chart and gold calculator for any jeweler's website. Two lines of code.
Get the code →A diamond loses most of its value the moment you buy it
Every jeweler 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 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 jewelry. It is an argument for knowing the number before you need it.
Retail against real resale
Round brilliant, G color, VS2, Very Good cut, GIA graded.
| Stone | Typical retail | Realistic resale | You 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.
Train your eye
One stone a day, drawn to scale on a finger. Guess its weight; see how far off you were. Most people are 30% out on day one and under 10% within a fortnight.
Train your eye
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.
Your record
Past stones
Missed a day? Every previous stone is still playable.
Know when your jewelry 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 — nothing else, ever. Want a report right now? Value your piece and download it instantly, free.
The questions people bring here most
Each answered with a real number, on its own page.
Common questions
Is CaratBase free?
Yes. Every calculator, chart and reference page is free to use, with no account and no sign-up. It costs $0, always.
What is the difference between retail and resale value?
Retail is what a jeweler would charge you for the piece today. Resale is what you would actually be offered when you sell it. For natural diamonds our resale figures currently sit at roughly 25–40% of retail, and for lab-grown diamonds at roughly 5–12%.
How does CaratBase value a diamond?
It starts from a per-carat price curve that jumps at popular weights such as half a carat and one carat, then applies multipliers for color, clarity, cut and shape, a lab-grown factor and a discount for uncertified stones. Side stones are priced one by one. The full method is on the How we value page.
Is a CaratBase figure an appraisal?
No. It is a price model, not an inspection, and it cannot see damage, fluorescence, brand or antique value. For insurance, probate or a legal matter you need a certified appraisal from a qualified appraiser.
Where do the gold prices come from?
Gold and metal prices are refreshed automatically from live spot prices, then shown per gram for every karat together with what a scrap buyer will really offer.
Does CaratBase store my jewelry details?
Pieces you save in My vault stay on your own device. CaratBase does not buy or sell jewelry.