Meet Rubel & Ménasché, Supplier of Perfect Stones to High-End Jewelers

Looking for D-E-F color goods that are VVS2 or better in clarity? Call on Paris-based Rubel & Ménasché, the go-to diamond source for many high-end jewelry houses (including Van Cleef & Arpels) in need of top-quality stones.

I didn’t stumble upon the firm at a show (it doesn’t exhibit at them). Instead, I was invited to visit the company’s offices—located a block away from Angelina of the hot chocolate renown—by communication manager Elodie Daguzan, who gave a friend and me a tour before the Baselworld 2015 fair.

Rubel & Ménasché is a 65-year-old firm specializing in high-end small, mostly round goods, and it re-cuts baguettes to fit the precise needs of high-end jewelry’s often-demanding clients. How demanding? Rubel & Ménasché can fill memo requests within a few hours for local clients (it is located on the Rue de la Paix) while adhering to patrons’ specific quality requests—no fluorescent stones allowed!

“In daylight, you might look at diamonds with fluorescence and think they’re oily or milky because their bluish tones emerge,” explains Daguzan.

As part of the Antwerp-based Dali Diamond Group—one of the Forevermark suppliers, as well as a De Beers’ sightholder since 1969 and an Alrosa partner since 1992 (Daguzan maintains that Dali is the third biggest client of Alrosa)—Rubel & Ménasché has a vast and constantly refreshed inventory classified by GIA and HRD graders. “Most of the goods we get are from Russia,” she explains.

And what an inventory it has: Upwards of thousands of carats, including certified stones starting at 0.3 ct., are always available. But it’s not the quantity of stones for which brands rely on Rubel & Ménasché, it’s the consistent quality of DE to FG color and IF to VVS2 clarity. Yes, the firm is a middleman, but an important one for brands that need a vast, unchanging inventory of particular stones.

Part of the premium included with buying from Rubel & Ménasché is its rigorous sorting process. All stones are checked under white light, and anything under a G color is rejected. To weed out fluorescence, diamonds are also checked under ultraviolet lamps, and any with a greater than medium fluorescence is returned. Diamonds are checked according to GIA criteria—think stones graded by DE to FG colors—employing a Sortoscope to examine stones under 2.5 mm in size and a 10x loupe for those above 2.5 mm. (Sortoscope also allows stones to be viewed at 10x.) Stones below VVS2 and those with a make grade below Very Good are rejected. And to further avoid mistakes, a minimum of two Rubel & Ménasché sorters carry out inspections in house. Additionally, 2,000 stones are chosen at random each month and sent to various labs to ensure the rocks aren’t treated or synthetic. “This is also to ensure that our grading quality is even and constant,” insists Daguzan. “We are checking ourselves.”

Sorting and grading, meanwhile, happen by relying on a white piece of paper, not a master set of stones like GIA graders. The paper itself isn’t special—“it’s plain, really white with a hint of blue,” says Daguzan—but when stones are aligned on it under white light, it’s perfect for grading multiple stones at a time. Master stones, meanwhile, are fine for sorting single stones at a time, but not batches of tiny rocks. After all, Rubel & Ménasché processes thousands each month.

“The core of our business is mass luxury,” explains Daguzan. “Our sorters are able to distinguish the middle range of a color, to get the best part of an F color, not the lowest part. Clients want us to sort more stones to find the best VVS—with inclusions on the side that are not dark. This is our value. The difficulty? Finding and staying on top of supply.”

Rubel and Ménasché sorters ferret out fluorescent stones because in daylight, their bluish tones appear oily or milky.

Rubel & Ménasché sorters ferret out fluorescent stones because in daylight, their bluish tones appear oily or milky.

Rubel and Ménasché employees grade color against an ordinary piece of white paper.

Rubel & Ménasché employees grade color against an ordinary piece of white paper.

Rubel and Ménasché staffer sorting diamonds

A staffer uses a Sortoscope to assess make and clarity grades.

Graffiti-street-art-inspired signage in a Rubel and Ménasché conference room in Paris headquarters.

Graffiti-street-art-inspired signage in a Rubel & Ménasché conference room in its Paris headquarters.

A parcel of diamonds ready for sorting.

A parcel of diamonds ready for sorting.

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