How CaratRadar Prices Diamonds

At least daily, and often more, we collect the public listings of certified loose diamonds from online diamond retailers. So far we have tracked 25+ of the major online retailers, and the list keeps growing.

Each listing gives us the store’s asking price and the stone’s details from its grading report: the grading lab and certificate number, shape, carat weight, color, clarity and cut. Natural and lab grown diamonds are kept apart, and the CaratRadar Fair Price never mixes the two.

Every certified diamond has a grading report from a lab, such as GIA or IGI, with its own certificate number. When two stores list a diamond with the same lab and the same certificate number, it is the same physical stone.

So on every diamond page we show the prices from all the stores that list that stone, from lowest to highest. This is the comparison no single store can give you.

The CaratRadar Fair Price is our benchmark for what a well priced diamond of a given kind costs at online stores today. You see it on diamond pages and in the diamond price calculator.

How it is built

• We group comparable listings: the same type (natural or lab grown), shape, carat range, color and clarity, and the same grading lab wherever we have enough of them. For round diamonds the cut grade counts too.
• We look at the asking prices across the whole group, from every store that lists such stones, so no single store sets the number.
• Unusual prices, very high or very low, do not move it: the method is built to ignore the extremes.
• It is not a simple average of asking prices. It reflects what a well priced listing in that group costs.
• Every CaratRadar Fair Price is recalculated as new listings come in, at least daily.

The range and how sure we are

Next to the CaratRadar Fair Price we show a range: where well priced comparable listings sit today. A price inside it is in line with the market. A price well above it is worth a closer look.

For every CaratRadar Fair Price we also keep a confidence level, based on how many comparable listings and stores stand behind it and how closely their prices agree. When there are not enough comparable listings, we show no Fair Price at all rather than guess.

Our diamond price pages show natural and lab grown prices by shape and carat size. For each page we take every matching diamond with a live price and count each stone once, at its lowest price across stores. From those prices we show the range, the average and the median, which is the typical price: half of the diamonds cost less and half cost more.

A stone whose prices across stores are too far apart to be believable is left out as a likely data error.

We collect new listings and recalculate every number at least daily, and often more, so what you see reflects the current online market.

Stores can change a price at any time during the day, so a store’s current price may differ from ours. The store’s own page is always the final word.

• These are asking prices, not sale prices. Stores offer discounts, financing and promotions we do not see.
• Retailers change prices and sell stones. A listing can change or disappear before our next update.
• Labs grade differently. The same color or clarity grade from two labs does not always mean the same stone, which is why the CaratRadar Fair Price compares stones from the same lab wherever it can.
• We do not inspect diamonds. We rely on the grading report and the store’s listing.
• The CaratRadar Fair Price is not an appraisal, an insurance value or a resale value, and it is not an offer to buy or sell a diamond.

CaratRadar does not sell diamonds. We earn money by selling pricing data and tools to diamond retailers and jewelers.

No store can pay to change the CaratRadar Fair Price or our price data. The price list for a diamond is always sorted from lowest to highest. If we ever show a paid placement, it is clearly labeled Sponsored and kept apart from the price list.