The brand

Tahiti black pearl expert

Find out about William's journey to build the Tresor Noir brand and become a true black pearl expert.

William De Marsangy - Créateur et fondateur de la marque de bijoux Trésor Noir
William de Marsangy

Créateur - Trésor Noir

Discover my background 


Thanks to the award of Gemologist of the Year in Spain and the 1st prize in the sector: Luxury Products and Jewellery by the magazine: AI M&A Award, William de Marsangy has become a reference in the jewellery scene.

Always helped by his faithful designers, the success of his creations is the result of a fine, simple and modern inspiration.

In short, unique handmade jewellery.

In an era of multiplication and large-scale work William draws his energy from his travels and the people he meets along the way.


After 5 years in French Polynesia, he became one of the few true ''Black Pearl Expert" from Bora-Bora with numerous stays in pearl farms where he was trained in the magical process of the birth of the pearl.

In 2006, he graduated in London as pearl expert from the GIA (Gemological Institute of America), the jewellery world reference.

From there Tresor Noir and William de Marsangy can follow the GIA convention to give a certificate of authenticity to each pearl purchased.

In 2008 he set up his first jewellery store Bora Bora.
An encounter will change his life. His wife, a Mauritian girl, who worked in a Resort where he was exhibiting his creations during fashion shows.


It's done in 2010 when William settled down in Pointe aux Cannoniers and created the Atelier by William which became, 2 years later Tresor Noir.

Since then, he developed the brand and his work is shown in the best resorts of the island.

His jewellery has been exhibited on various occasions, in Las Vegas, Paris (Bijhorca) and Éclat Tropicale in Mauritius and he was designated in 2014, Leader in the Industry sector: Best CEO by the magazine "Acquisition International".

He has been presented in the local press as the Saint Laurent of the Pearl and is helping the local designers.
More than an invitation to travel, this young man full of passion and enthusiasm will amaze you. Do not hesitate to contact William to reserve a privileged moment and choose the jewellery of your dream with him

Pearl Workshop

"You already are a unique creation" William de Marsangy,  Founder, Trésor Noir

Gemologist and black pearl expert, Wiiliam operates the Tresor Noir brand in Europe and in French Polynesia.

All the jewelry made by Tresor Noir is hand made.

Each pearl comes with its authenticity certificate which certifies its origin and quality.

The Press talk about us

William de Marsangy: le St Laurent de la perle