Gema & Co

Gema & Co is a moissanite and lab-grown diamond retailer that trades entirely online, out of San Francisco, with no boutique anywhere in Switzerland or Zurich to walk into. It has been in business since 2017, and by its own count on the homepage has filled more than 19,000 orders in that time, which puts it well past the point of being a new or untested storefront. For a Zurich-based reader used to booking a consultation on Bahnhofstrasse, that absence of a shop matters more than anything else here: everything from browsing to sizing to the final order happens through the website, an email address, or a text line, in English, run out of Pacific time.

What you get

The catalog splits cleanly into moissanite and lab-grown diamond lines, across engagement rings, wedding bands, earrings, and loose stones a buyer can set separately, plus a custom design route for anyone who wants a one-off piece built from scratch. The homepage that loaded for this review had already switched itself to Switzerland: a country and currency selector in the header read "Switzerland | CHF" among dozens of other markets, and every price on the page was already quoted in francs rather than dollars. Loose moissanite stones start at CHF 25 for a small princess cut and run up to CHF 107 for a cushion cut, and finished ring settings, before a stone is added, span CHF 576 for a plain solitaire mount to CHF 659 for a pavé or bezel design. Every setting is described as made in the United States, 100% of it, in casting facilities the company names as California and South Florida, rather than sourced from an outside manufacturer.

What stands out, and what to verify

Moissanite itself is a genuinely interesting stone to build a business around. It was first found in a meteor crater in 1893, long before anyone could grow it in a lab, and the version Gema & Co sells has a refractive index the site puts at 2.65 to 2.69, against 2.42 for a natural diamond, which is the technical reason it throws more visible fire under ordinary light. On the Mohs hardness scale the company quotes its stones at 9.25, which is high enough for genuine day-to-day durability rather than a number picked for effect.

Where the site is less careful is in how it talks about ethics and sustainability, and this is worth spelling out plainly for a category that exists specifically to reward verifiable sourcing over a nice-sounding label. Gema & Co describes its stones and metals as "100% conflict-free" and "environmentally friendly," and says its platinum and gold come from recycled, post-consumer sources. None of that is backed anywhere on the site by a named auditor, a chain-of-custody certificate, or a recycled-content standard a buyer could look up; it is the company describing its own supply chain in its own words. The one part of that story with a real document behind it is the stone's origin: a lab diamond graded by the International Gemological Institute (IGI) or the Gemological Institute of America (GIA), the same two labs the company says grade mined stones, comes with a report confirming it was grown rather than mined, which is genuine evidence against the specific harm the phrase "conflict-free" usually points to. The environmental numbers quoted on the site's own lab-diamond page, that a lab-grown carat uses 18 gallons of water against 126 for a mined one, and releases a few grams of carbon against 57 kilograms for mining, are stated flatly with no study, agency, or year attached to either figure. A second badge shown next to the IGI mark, reading "National Jeweler Association Certification," does not correspond to any accrediting or standards body this review could find; it turns up only in other, unrelated retailers' own marketing copy online, never on an association's own site, so it reads as a logo rather than a credential until the company says what it actually certifies.

How it's organised

There is no showroom, no appointment book, and no live video consultation offered the way some competitors in this category run one. Support runs by email and by text to a single US number, with hours given as Monday to Friday, 9am to 5pm Pacific, which for a Zurich buyer means the working day barely overlaps at all: a message sent on a Zurich morning lands in the middle of the US night. Payment runs through the ordinary card networks plus Apple Pay, Google Pay, Shop Pay, and Venmo, and the company also offers instalment financing through Bread Pay, underwritten by Comenity Capital Bank, with a credit decision arriving in seconds and no stated penalty for paying it off early. Nothing on the payment page says whether that financing extends to a Swiss billing address, so treat it as a US-market feature unless support confirms otherwise. A bank wire earns a 1.5% discount for US and Canadian buyers, but a wire from anywhere else, Switzerland included, is charged a flat $35 processing fee on top.

Shipping, customs and the Zurich question

This is the point the brief for this listing specifically asked to be checked, and it does not entirely hold up. Gema & Co's own shipping page states plainly that "shipping is available for the United States, Canada, Australia, New Zealand, and most European countries at this time." Switzerland is never named. The country selector in the header does let a visitor pick Switzerland and see francs, which is a real signal that the checkout has been configured to accept a Swiss address, but it is not the same as the written policy actually confirming the destination, and Switzerland sits outside the European Union that the phrase "most European countries" would most naturally describe. Free shipping only applies to US orders over $250 in any case. Every piece is made to order, with the site quoting 3 to 4 weeks of production before anything ships, after which delivery is quoted at 3 to 5 business days domestically and capped at 9 business days for an international parcel once it leaves the workshop. On duty, the site's own wording is that it "will pay all required US customs fees at time of shipping," but adds that "each individual country will have their own customs and trade rules and additional fees may be required for release to you," language that puts Switzerland's import VAT and any handling charge on the buyer at the door, rather than folded into the checkout price the way a couple of other sellers in this category now advertise. Anyone in Zurich actually placing an order should confirm both points, that Switzerland ships at all and what lands on the doorstep afterward, before treating either as settled.

Returns, warranty and resizing

The published return window is 30 days from receipt, for anything unworn and in its original packaging, with a $25 charge if the warranty card is missing and only one return or exchange allowed per household. Bespoke and final-sale pieces are excluded outright, and a custom order can still be unwound before production starts, minus a $100 non-refundable design fee. Refunds take 7 to 10 business days to process once a return is inspected, minus a 7% origination fee if the original purchase was financed, and international return shipping back to the US is quoted on the returns page at $16 to $80, depending on how much insurance the buyer wants on the parcel. Warranty coverage splits in two: the stone itself, moissanite or lab diamond, carries a limited lifetime warranty against manufacturing defects and discoloration, while the metal setting gets a separate two-year warranty covering ordinary wear and tear, with anything beyond that reviewed case by case. What is not published anywhere, across the shipping, returns, warranty, or FAQ pages, is a resizing policy: no free resize, no fee, no turnaround time is stated. For someone who expects to need a ring resized after a year or two in Zurich, that is a real gap next to competitors who spell it out, and worth asking about directly before ordering rather than assuming it works the way a local jeweller's does.

Who it suits, and the verdict

Gema & Co suits a Zurich-based buyer who is comfortable choosing a stone and setting from photos rather than a countertop, wants a genuinely wide moissanite range at prices that undercut a mined-diamond equivalent, and does not mind a 9-year-old, high-volume US operation over a boutique relationship. The lifetime stone warranty is real and clearly written, the Swiss-franc pricing already on the homepage removes the currency guesswork a lot of US sellers leave to the buyer, and the moissanite science behind the sparkle checks out against independent sources rather than being invented for the site. Set against that: the shipping policy never actually names Switzerland, import duty is left for the buyer to sort out on delivery rather than pre-paid, resizing is not addressed anywhere, and the ethical-sourcing language leans harder on marketing than on anything a buyer could independently verify beyond the stone's own lab report. None of that is a reason to skip the site. It is a reason to email support and get Switzerland confirmed in writing before a deposit changes hands.