Two separate experiences with this jeweller, and unfortunately both ended very poorly.
I had two separate experiences with this jeweller, and unfortunately both ended very poorly.
His profile in instagram:
zlatnik_klenotnik
1. Diamond purchase
In October 2024, my wife and I purchased a 1.02 ct natural GIA chameleon diamond from Johann for €4,500. This was not our first purchase from him. We had worked with him on previous orders as well. There were some issues with those orders, but nothing comparable to the present situation.
We trusted Johann’s professionalism and his assessment of the diamond’s market value, investment potential and future growth. This was an important factor in our decision to purchase the stone.
When we later tried to sell this specific diamond through professional buyers in Europe, several companies declined to purchase it and raised concerns about its inclusions, clarity, colour characteristics and overall marketability. One written professional valuation was only £200–500.
An Antwerp company also told us that it would be difficult to sell our diamond at the any price. As a comparison, they showed us a 1.01 ct Pear Chameleon offered at $3,500, but explained that this was a substantially superior stone in terms of its characteristics and overall quality.
These were not internet advertisements or random opinions. They were direct responses from professional companies that had reviewed information about our actual diamond. I can provide the names of these companies to anyone who wishes to verify the information.
We presented this information to Johann and asked him to help resolve the situation. His final position was that he had done nothing wrong, that he still stands by his statement that the diamond has “growth potential”, and that the responsibility was essentially ours for not having independently researched the market before purchasing it. He declined to offer any solution or help us recover the €4,500 or even to help in selling.
2. Custom-made desk sculpture
I also ordered a specific custom-made sculpture and paid a €400 deposit. Johann warned me that they had never made such an item before and that it could take time, which I accepted.
After approximately 6 months (in March 2025) and repeated follow-ups, Johann told me they had tried but were unable to complete it. I accepted that outcome. The problem was the refund: it took another 6 months, possibly longer, to recover the €400. Johann repeatedly stopped responding to my messages or even calls. When he did respond, he asked for my bank details and then disappeared again.
Eventually, the only way I managed to receive my money back was by asking a friend to visit the Cylinder office several times and wait for Johann personally. At that time, I had already left Slovakia due to work in another country, so I could not make repeated personal visits myself. On several occasions, my friend was told by Johann’s assistant that he was not available. Only after a confrontation at the office did Johann eventually appear from another office and deal with the matter personally.
I am attaching screenshots of the correspondence regarding both the sculpture and the diamond as documentation that these situations are genuine and based on actual transactions.
These experiences left me seriously disappointed. My concern is not simply that a custom project failed or that the diamond market changed, but how the problems were handled afterwards: poor communication, long delays, and ultimately no willingness to help resolve the diamond issue.
Based on my experience, I strongly recommend obtaining an independent professional valuation before purchasing any significant stone from this jeweller, particularly diamonds, rather than relying solely on the seller’s assessment of their market value.
After these experiences, I personally would not purchase anything from Johann again, regardless of the circumstances.
This review reflects my personal experience, and I have written correspondence and documentation supporting both situations.