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  • Writer's pictureIlana Brandwain

Zimmi Diamond Polishing: Inside the Polisher's Workshop

As a diamond jeweller and being married into family of diamond experts (my husband is a third-generation diamond trader), it comes as no surprise that I am always on a path of learning and challenging myself within the diamond world.

My first lesson came many years ago when I discovered more about the mining process and how our diamonds – specifically Zimmi Diamonds – are ethically and sustainably sourced. Thanks to our family connections with the diamond mines in Sierra Leone and Liberia, I have visited our family-leased operations several times and seen first-hand the stones being unearthed straight from the riverbeds of the Manu Delta and the positive impact diamond mining has on the whole community.

And then there were the lessons I have learnt over the past seven years since I launched our sister company in Antwerp, Noble Fine Jewellery about the diamond retail market and selling fine jewellery. The value and magic these stones hold having taken billions of years to form is still as exciting and thrilling as when I first began the business: how the different cuts and carats and clarities can transform a diamond completely and how they still remain one of the world’s most sought-after commodities.

polished oval zimmi diamond

However there is one vital and essential lesson that I have been fortunate enough to witness as a bespoke jeweller, but I have never been able to participate in: the transformation of a diamond from the rough stone we found in the riverbeds of Sierra Leone and Liberia to the stunning polished gem we sell in our finished pieces.

Thankfully earlier this year, I was able to take one of our Zimmi Diamonds through the cutting and polishing process. Working with the professionals and Antwerp’s amazing artisans, I was guided through every step of the process and could witness first-hand how painstaking and precise the polishing process needs to be.

The skill and craftsmanship required to ensure a diamond is revealed in the best of its glory, all the while feeling the immense pressure that at any time the diamond could shatter and all would be lost – makes something seemingly so straightforward become suddenly very dramatic.

For months, my days were spent at the polishing wheel in a secure workshop within the Antwerp Diamond District. Under intense bright lights surrounded by heavy tools and industrial equipment, a diamond polishing studio is a million miles away from the glamour I am used to when working with clients. The silence and the focus in the room is only broken by the high pitched scraping noise of the polishing wheel as it rotates at up to 3,500 rpm as the diamond dust tries to cut away the rough surface resulting in temperatures of up to 950C! Yet there is something so authentic and raw about this room.

It is only now, several months (and a global pandemic) later that the polishing process is over and I feel I can share the story of our Zimmi Diamond. Taking it from the riverbeds right through to today, where it is sparkling and ready for sale. So let me take you right back to the beginning…

Prepare for Planning: The diamond world has advanced thanks to the technology and science we now have available for studying the stones and understanding the potential of what lies beneath its rough exterior. To believe that only a generation ago, none of this was possible and our polishers were doing everything by hand is just incredible and it was much more speculative so you had a manufacturer (planner), a polisher and a cutter working on stones. Today, each stone is scanned and analysed to establish where the finished gemstone can be outlined. We have to consider how much polished diamond can we get from the rough to get the best diamond possible in terms of colour, weight and clairty and how quickly it will take to polish and get them ready for us to use in our jewellery pieces. And with this Zimmi Diamond (and in fact, all coloured diamonds), we also need to consider what is the best cut to accentuate and intensify the intense yellow colour.

planning marking rough zimmi yellow diamond

Sawing Direction or Cleaving Direction: this is the stage where the decision is made to either use the saw or cleave of the stone depending on how the diamond was formed and it’s the laser that draws this direction.

Preparing for polishing: After the stone has been sawed or cleaved the stone will have to be cut. Each rough diamond has a cutting plan that is marked up to show the facets and angles the polisher wants to achieve. There are no guarantees that the stone will not shatter or be destroyed during this process which is done with a diamond saw or laser. Regardless of the science and technology that has been done, success here also comes down to the skill and expertise of the polisher who will be able to navigate this process and establish the rough stone and size of the final gemstone.

Uncovering the sparkle: It can take many MANY hours on the polishing table to begin revealing the beauty underneath. Here we can see the essence of the Zimmi begin to show itself after several hours in on the diamond polishing wheel. In order to polish the stone, the Zimmi is held in a polishing tang which turns at 360 degrees at a specific angle to polish the facets (or sides) of the stone. It is then placed on the diamond wheel carefully until the diamond touches the wheel which uses a paste made from diamond dust – hence the phrase ‘diamond to cut diamonds’ – to create the first (the table, top) of the 57 sides (or facets) that our stone will eventually have.

Quality Control: A diamond polisher is constantly reviewing their work to ensure there are no marks or abrasions left on the stones. It is essential that all 57 facets are equal and symmetrical as the value of the stone and the final look of the diamond is only guaranteed with this level of detail and constant monitoring during every step of the polishing process. Using these loupes to magnify the stone surface x10 (there are higher magnifications available for diamond polishers) allows us to check the finished effect.

diamond polisher workshop antwerp

Behind the scenes: While a polishing studio may be a world away from the glamour and style of the diamond jeweller’s atelier, here is where the magic happens – where the diamonds are transformed from the rough and unpolished rocks that surfaced from the depths of the earth ready to be transformed forever. Here is the polisher’s wheel that will use the paste made with diamond dust to achieve a strong enough buffer against the rough diamond surface.

Getting there… after 2 months of preparation and polishing, the gemstone is starting to emerge. There is more to be done with the facets and bringing out the natural yellow colour but just this process alone has opened my eyes to the patience and skill that is required to get to this point – elements that I do not claim I have! But understanding the whole journey a diamond makes from the depths of the earth to my clients final jewellery piece is something that I feel will only make me a better jeweller and give me a deeper understanding of what is needed to make something so precious and eternal. And it is so exciting to see what nature and man can produce together.

finished polished zimmi yellow diamond antwerp

The Finished Stone. My first polished diamond, and even more importantly for me… a Zimmi Diamond. It took a tota of 80 days to create this beauty and while I know one of our clients will love it just as much as I do (especially if it’s in one of our engagement rings!) – I can’t help but want to keep it for myself. But for now it is onto the next one…

This incredible experience would not have been possible without the patience and friendship of Frederik Mulier & Gemtech , who guided and helped me through the process. Their skill, expertise and knowledge are an inspiration to me and their good humour and willingness to welcome me into their world will be forever remembered with gratitude.

To discover more about Zimmi Diamonds or to get in touch with our Diamond Expert and arrange your own tour of Antwerp’s Diamond District and our polishing workshops, simply email or call +32 497 239 403.


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