Inside DIATHEKE, Rosy Blue's manufacture in Geneva

A short distance from Geneva, the Plan-les-Ouates industrial park is home to world-famous names in watchmaking, their gigantic manufactures almost dwarfing the more modest facilities of DIATHEKE. Since June 2024 the company founded by Théo Massaoutis in 2017 has occupied a 1,300 square-meter (14,000 square feet) contemporary building. The 32 staff are shared across the 3D design and technical development studio, the nine CNC machines for precious metal manufacturing, the gem-setting workshop, the jewelry and high jewelry atelier, two colored stones lapidaries, polishing and final assembly of exceptional pieces. In 2025 the Antwerp-based diamantaire Rosy Blue invested in the company’s expertise, with the objective to offer watch and jewelry brands a complete range of services, from the preliminary drawing to watch assembly, from the initial sketch to series production of jewelry or creation of one-off high jewelry pieces, together with the technical development and manufacturing of the full range of watch and jewelry components. The aim, says Rosy Blue NV CEO Ravi Bhansali, is to “support customers with their needs, help them achieve their vision, and respond quickly and precisely to resolve technical challenges.” /public-objects/3fe4d1fc-1d04-4b1b-b23e-ceb15c416946-4f5b77a3-e0fb-45d4-8b9e-8725a13c8861-PHOTO-2026-08-25-11-40-44.webp Image sélectionnée AGILITY AND INNOVATION This vertical integration gives DIATHEKE greater agility to serve the needs of the leading luxury players. Having built its reputation as a partner to the watch industry, in particular the creation of spectacular gem-set pieces, it has since extended its expertise to high jewelry: a division within the company that now accounts for half of its business. “We have the capacity to adapt quickly and continually advance our technical capabilities through increasingly complex projects,” notes Théo Massaoutis. Appointed in October 2025, Ludovic Lesemann brings his skills and experience to bear as the head of the jewelry department, after twenty-five years as an independent developing technical innovations for major brands. This specialist in transformable jewelry and miniature mechanisms is also exploring innovative materials, including a shape-memory alloy, used in the medical sector, as a solution to very real problems such as how to precisely adjust a choker to fit a customer’s neck. DIATHEKE patents every one of its inventions before offering exclusive rights to a watch or jewelry brand — it probably won’t be long before the ingenious mechanisms currently taking shape behind the manufacture’s closed doors make it to market. /public-objects/565b3ccb-25f2-491d-acb7-7bb4cf4ed4da-d687a150-74d6-4021-ac53-8a68ed4207e3-Sapphire%20rough%20Z62_8827.webp Image sélectionnée Further proof of this agility, DIATHEKE recently supplied an up and-coming brand with finished watches, from the design all the way through to the end product, in a timeframe few others could match, its larger competitors often lacking the necessary flexibility. Alongside this adaptability and specialized “made in Geneva” know-how, Rosy Blue’s acquisition of a majority stake in its capital adds another string to DIATHEKE’s bow. An important midstream player, Rosy Blue gives the firm direct access to the diamond sector, making it one of the very few companies in Geneva with mine-to-market capability. This mine-to-market expertise now extends to colored stones, too, thanks to the recent partnerships Rosy Blue has concluded with colored gem mining companies. Furthermore, in order to secure colored gemstone cutting operations, Rosy Blue has opened a facility in Bangkok which employs 35 people and supports DIATHEKE on a daily basis. /public-objects/0d227b6f-b7c5-4f07-b983-16f606fb5299-b543830e-a81a-4188-820d-5a4864509160-PHOTO-2026-08-24-06-42-55.webp Image sélectionnée With two complementary forces driving its growth, DIATHEKE is ideally placed to cement its position as a reliable and trusted long-term partner to leading houses from Geneva to Place Vendôme. The family heritage and industrial might of a giant in the diamond sector paired with the agility and expertise of a Swiss standout constitute assets that few subcontractors possess, in a market where trust is earned over many years. ROSY BLUE, OVER 65 YEARS OF DIAMOND The Rosy Blue story began in 1960, when Arunkumar Mehta and his uncle, Bhanuchandra Bhansali, established B. Arunkumar & Co. From its origins in Mumbai, the family firm soon expanded internationally: Antwerp in 1973, the US and Asian markets as of 1974, then Tokyo in 1978. In 2000 sales hit the one-billion-dollar milestone and the group took its new name: Rosy Blue. A De Beers sightholder since 1969, Rosy Blue is a leader in the midstream segment, operating between the mine and prestigious clients in the luxury sector. It trades roughs and manufactures diamonds at its four facilities, where it employs more than a thousand highly skilled staff. This industrial expertise, backed from the beginning by family ownership and strategic management alongside professional governance, has earned Rosy Blue the trust of leading jewelry houses to secure a reliable and traceable supply of stones. Indeed, Rosy Blue is a pioneer in sustainable and ethical procurement. As a founding member, in 2005, of the Responsible Jewellery Council, it is one of just two midstream companies among the RJC’s 14 founders, alongside brands such as Cartier and Tiffany & Co. The group has made traceability a strategic priority, leading the way for the entire sector, and extending its commitment to sustainability through its recent Net Zero 2050 target, validated by the SBTi in 2025. /public-objects/6181584c-977a-4847-acca-d485a21720b7-8cf3974f-8f7a-460f-abb5-d923dbb86e3d-PHOTO-2026-08-25-20-24-25.webp Image sélectionnée