Our Diamond Experts Carry Out a Professional Valuation Process

To value large amounts of mixed small-sized recycled diamonds of different grades and shapes (called “melee” after the French word meaning “mix”), we cannot grade and value each stone individually. Instead our highly-trained buying team will follow a structured, transparent process.

Remove non-diamond from diamond: as far as possible we remove CZ and other diamond-simulants from the batch; if there are large volumes of CZ amongst the diamond, we may need to take a sample to estimate CZ content, and/or to carry out a CZ separation service (for a small charge).

Sort into size bands: for loose diamonds, we sort into broad size-ranges using specially-made diamond sieves; for diamond-set jewelry, we sort into rough groups according to the size of the largest diamonds in the jewelry. For any diamonds larger than 0.20 carats, whether or not set in jewelry, we will review each stone individually.

Diamond grading: for each size band in the smaller size-ranges, we take a random sample of 20-30 diamonds, and sort into corresponding groups for shape (round cuts from princess, old cuts from new, broken etc.), color and clarity, and measure the weight of each group. For larger diamonds, we grade and value each stone separately.

Diamond valuation: we sell large volumes (30-50,000 carats each month) of diamonds to the market through our WPSales tender auctions and brokerage in New York and Hong Kong on a regular basis, and as such have a unique view of the current market prices for each shape/grade/size of diamond. By applying a price per carat for each sorted group which is reflective of this market, and the relative weight of each group compared to the whole of our sample, we calculate a price per carat to be applied to each size band to come up with the best possible total price for your batch.

Metal assessment: while we are not precious-metal buyers, we would rather purchase diamonds set in jewelry than face the risk of breaking them by manually removing them from their settings which substantially reduces their value. We pay a very competitive market price for any precious metals in addition to the diamond value. We test precious metals using an x-ray gun, or a more traditional acid touch-stone method. To value the precious metals for diamond-set jewelry, we will sort into the different constituent metals, for example 18K and 14K gold, platinum etc. and pay according to total weights of each metal.

Our offer / payment process: we communicate the total price to you either in person during a valuation visit, or by telephone or email if you have shipped diamonds to us. If you accept our offer, we arrange immediate wire transfer to your account, with funds often arriving the same day. If we have carried out a personal valuation visit, we will leave the diamonds on your premises (generally in a tamper-proof bag) and only when funds have arrived will we arrange shipment at our cost to our New York office.