Diamond Exchange, Capital C Amsterdam


Heyligers Design + Project
Amsterdam, Netherlands | View Map
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Former Diamond Exchange, Capital C

ZJA en tant que Architectes.

A proud monument

As a building and as an institution the Diamond Exchange, built in 1910 after a design by Gerrit van Arkel, crowned the heyday that counted as a second Golden Age for the city of Amsterdam: the economic boom following the 1880s, that restored the city as a metropolis for industry and trade after a century long slump. At that time Amsterdam had developed into one of the most important centers for the international diamond industry. And all that can be sensed in the idiosyncratic design of the Diamond Exchange. Modern and business like in its rhythmic structure, but also full of classical elegance with its striking bell tower and sophisticated decorations. This city jewel in its modest Art Nouveau style is officially acknowledged as a national monument of the first order.

At the beginning of the 21st century the building was in a poor state. After several additions, a fire and various renovations much of the original charisma was gone. It was glossed over, hidden by the distraction of monotonous add-ons.


A new beginning, a new century

The new owners Zadelhoff & Sijthoff envision a role for the Diamond Exchange in what is considered a new heyday for Amsterdam, now as an international hub for the creative industry and information technology. In order to meet that role envisaged as Capital C a thorough renovation was called for and ZJA Zwarts & Jansma Architects were asked to produce the design. That design has in mind three objectives, first of all to restore the original qualities of the Diamond Exchange in its full glory. Secondly to adapt the interior for use as a modern, flexible office environment and thirdly to build a contemporary addition open to the public.


Renewed Diamond Exchange meets the city

The largest addition consists of the restaurant and the terrace on the seventh floor, under an oblong dome. The construction on the roof is based on the grid shell principle, in which the constructive force is absorbed by the double curvature in the roof’s surface. That allows for an enormous freedom in shapes and a large span without columns. The dome’s structure, covered with glass panels is transparent, light and open. By raising the floor on the sixth level the dome can appear even more free and slender. The addition stands free from the bell tower and is built well inside the original facade. Seen from the street the relationship between old and new are evident: the Diamond Exchange takes the spotlight and the dome is a supporting addition. The new public space makes a transparent and inviting gesture, reflecting light and sky in all directions.


A revitalized monument

With this renovation the Diamond Exchange is to be restored to the original design by Van Arkel. That is paramount. The new dome echoes the dome of the bell tower, but with its multifaceted glitter also refers to the past of the building. The bell tower remains the landmark. At its foot, along the Weesperstraat, an inviting entrance is planned, surrounded by green zones.


Historically an exchange is the meeting place of markets and people, goods and ideas, and that is how the renewed Diamond Exchange meets the city. Capital C offers a contemporary office environment inside a unique monument, and on top of that one of the most spectacular views over the city as seen from the roof with the stylish and iconic dome. The Diamond Exchange can again truly be a part of the city, as a center for the creative industry, as a public space with a restaurant and a space for art. And as a sparkling monument that is the image of the past and present of Amsterdam.


Diamonds are Forever

Octatube en tant que Fabricants.

A metamorphosis has taken place in Amsterdam on Weesperplein. The Diamantbeurs (Diamond Exchange) is a historic building that has been restored to its former glory with a striking addition! Over the full width of the building, Octatube has build a roof structure that is 10 meters high. As you can see, Diamonds are Forever.

To promote the diamond trade, the Diamond Exchange in Amsterdam was built in 1910. The well-known architect Gerrit van Arkel designed the building. In 2015 the building was purchased by Sijthoff Media Groep and Zadelhoff Beheer (formerly Beheer Brouwershoff). The Diamantbeurs is undergoing the transformation according to the design of ZJA Zwarts & Jansma Architects. All historical details will be done by Braaksma & Roos Architects. Octatube has been commissioned to realize the spectacular roof structure.

Premium design

The design for this project is very refined and innovative. The large dome, which is about 45x21x10 meters (lxwxh), consists of two floors and has a free form. Meaning it cannot be defined by a certain basic geometric shape such as a sphere or cube. The Octatube team has taken on the engineering (the constructional elaboration and structural calculations) of the design. Optimizing the shape in 3D and the parametric designing were particularly challenging.

Parametric design

Because of the free form of the design, all the parts (steel beams, glass panels, etc.) differ and each time they come together in a different geometric way. If anything in the design was adjusted, all parts would change. After all, everything was connected. This led to the idea to automate the design by developing a parametric tool that could convert the complex basic geometry into a detailed production model. 

The design was parametrically designed down to the last detail and from these models the productions were managed. By designing the project parametrically, the construction proved to be not only technically feasible but cost effective as well.

Here you can read more about how parametric design was applied in this project.


Besides the fact that Octatube developed software for this project in-house, a file-to-factory method was devised and implemented. For example, when a certain assembled element had to be manufactured, the necessary tube-laser cut steel parts were available on the same pallet. The parts were then assembled on an adjustable mould with supports, also known as a 'nail bed'.

Daniel van Kersbergen, engineer at Octatube: "All complexity is automatically extracted from the computer by using the developed software; the height, the position and the angle of the part. The geometry of the model is extremely complicated because everything is skewed. The nail bed ensures that all the complexity of the model can still be assembled in one go.

Complex welding

The welding work is difficult because of the complexity of the model. Using the nail bed, the welders managed to control the tolerances. 

Vincente Monteiro Chantre, foreman at Octatube: "The biggest challenge is to ensure that the fabrication is of the right size. If you weld, the material always distorts a bit. You have to be able to properly assess what the material is going to do. We determine our welding direction and position before we begin welding. The fact that the practical and theoretical part come together at an early stage certainly was an advantage.

Building Integrated Photo Voltaics (BIPV)

With a BIPV system, the standard PV panels are integrated into the building. BIPV always has a two-in-one function that combines the generation of solar energy with roofing, facades or glass. For the Diamond Exchange, the BIPV system is integrated in the glass panels of the roof. Each glass panel has a unique number and unique location on the dome. When delivering the panels, we therefore agreed in advance in what order and in what way the panels should be grouped on the glass stillage.


Corine Dikkers, project manager at Octatube: " The moment all parts on site come together and fit together perfectly, then you are really proud that such a design is made by Octatube. A lot of preparation goes into all phases of the project and so many people work on it. When it all comes together on site in such a short time (8 days, steel construction), you think: wow, there it is!

The roof structure designed by ZJA has a limelight purpose. You can easily see the transparent curves of the new structure from a distance. The glass roof structure refers to the history of the building as the centre of the international diamond trade. Like a cut diamond it shines in the light and makes the Diamond Exchange shine again.

(Photo's: J.W. Kaldenbach)

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