Diamondonline

Diamondonline runs a stone-first business from a small office on Kuttelgasse in Zürich's old town: no shop window, no walk-in counter, just GIA and HRD certified diamonds sold at what the company calls bourse price, meaning close to the wholesale rate rather than a boutique markup. If you already know roughly what you want, a certain carat weight, a colour and clarity grade, this is the kind of dealer built for you rather than for someone who wants to browse finished rings under glass. The founder, Nicolas David Karouni, is described on the site as a gemologist with over 25 years in the trade, and the business also runs a separate wholesale arm, Andkstone, supplying diamonds to goldsmiths and small jewelers rather than only end customers.

What you get

Everything runs through a personal appointment. The site asks you to propose two possible dates, or to reach out first by WhatsApp, phone or email, and the team will confirm a time to sit down together. That consultation covers diamond appraisal against GIA criteria, certification (the site states plainly that a genuine diamond carries a GIA or HRD certificate, and that Diamondonline will produce one if a stone doesn't already have it), buying diamonds and diamond jewelry back from clients, and building a custom engagement ring or piece around whichever stone you choose. The homepage was showing a specific loose stone for sale at the time of writing, an oval brilliant cut at 20.20 carat, VVS1 clarity and D colour (the top of the colourless scale), with a certificate available as a PDF download, which gives a useful sense of the level the business trades at day to day.

The educational content backing this up is solid rather than decorative. The site runs through the four Cs, cut, clarity, colour and carat, explains that the colour scale runs from D (completely colourless) down to Z, and even spells out that one carat equals 0.2 grams, the kind of plain-English grounding the category as a whole should be judged on. That matters more than a glossy gallery page for a buyer who wants to understand what they're paying for rather than just be sold to.

Pricing, and what isn't published

Nothing about pricing is public. There's no price list, no per-carat table, no ballpark figures anywhere on the site, only a form asking for your target shape and carat so the team can send a free, non-binding quote. Given the bourse-price positioning, that's consistent rather than evasive, wholesale-linked pricing moves with the market and doesn't lend itself to a static page, but it does mean you're negotiating from a personal quote rather than comparing published numbers before you ever pick up the phone. Anyone used to a fixed online catalogue should expect a more old-fashioned, conversation-first process here.

Reach, hours and language

The business operates from Zürich with a second office at 5 Avenue de Villiers in Paris, and the site describes further offices in Hong Kong and India, framing itself as an internationally connected diamond house rather than a purely local jeweler. For an expat buyer that international footprint is a genuine plus: if you leave Switzerland after a posting, this isn't a business that only exists inside one canton. The site itself is offered in German, English and French, so English-speaking newcomers to Zürich aren't limited to Google Translate, though the German-language pages are noticeably more developed than the English ones. Zürich hours, when the office is staffed for walk-ins rather than appointments, run Monday to Friday 10:00 to 13:00 and 14:00 to 18:00, with Saturday 10:00 to 18:00, and a mobile line is answered around the clock alongside WhatsApp.

Ownership and standing: what we could confirm

This is the part worth reading before you book anything. The company named on Diamondonline's own legal notice, in both the German Impressum and the English masthead page, is ANDK Stones Swiss GmbH, UID CHE-109.293.300, registered at the same Kuttelgasse 4 address the site trades from. Independent Swiss commercial register aggregators (northdata.de and lixt.ch both confirm this, and moneyhouse.ch's own listing states it directly) show that ANDK Stones Swiss GmbH is now in liquidation: a preliminary opening was recorded on 14 April 2025, formal liquidation opened on 16 April 2025, and a creditor deadline was set for 17 October 2025. In other words, the legal entity the website itself names as its operator has been winding up for well over a year, and neither the German Impressum nor the English masthead has been updated to reflect that.

There is a separate, active company on the Swiss register that also carries the Diamondonline name: Diamondonline Swiss GmbH, UID CHE-115.422.907, founded in 2010 and shown as active with a register update as recent as 26 February 2026, run by the same Nicolas Karouni. It would be reasonable to assume this is the successor now trading the site, but the public record doesn't confirm that cleanly. That company's registered address on file is Chrummwisstrasse 21 in Küsnacht, not Kuttelgasse 4, and nothing on diamondonline.com names it anywhere, not on the homepage, not in the Impressum, not in the masthead. We also found a Zürich court filing that names Diamondonline Swiss GmbH as a respondent and references the Kuttelgasse 4 address, giving it a 20-day deadline to respond to a court order; the subject of that filing and whether it has since been resolved were not available from public search results, so we're flagging it rather than characterising it. A Swiss trademark record for the Diamondonline name itself is registered to ANDK Stones Swiss GmbH, the entity in liquidation, which adds another loose thread rather than a tidy handover.

None of this tells us the business has closed. The website is live, the appointment booking process works exactly as described, and we found no closure notices, fraud reports or customer complaints anywhere in our searches, only the corporate paperwork above. But we could not verify a clean, documented succession from the liquidated entity to a clear active successor at the same address, and we'd rather say that plainly than paper over it. If you're placing a deposit toward a custom commission, ask directly which legal entity is invoicing you and issuing the certificate, and check its current commercial register entry yourself before you send money.

Who it suits, and the verdict

This is a good fit for a buyer who already understands the four Cs, wants a personal, appointment-led relationship rather than a browsing experience, and is comfortable negotiating a quote rather than reading one off a page. The international office network and multilingual site make it a reasonable option for someone who has just landed in Zürich and doesn't yet have a network of local jeweler recommendations. It's a weaker fit if you want a same-day purchase, a transparent published price list, or the reassurance of dealing with a company whose own paperwork is fully up to date.

The underlying expertise on display, the certification standards, the plain explanation of what makes one diamond worth more than another, and the appointment-first, no-pressure structure are genuinely good reasons to take a meeting here. Just go in with your eyes open on the corporate side: confirm who you're actually contracting with before any money changes hands, and treat the legal notice on the site as outdated rather than authoritative until you've checked for yourself.