123GOLD

123GOLD runs its diamond business from Switzerland, with stores in Wädenswil and Luzern and a ring configurator you can use online. The shop sells loose stones along with engagement rings and wedding bands, and you can build a setting around a diamond you pick. From 0.3 carat upward, stones are certified and cut to three-times Excellent, with grading by recognised labs such as GIA or IGI.

The site explains all four Cs (carat, cut, colour and clarity) so you can judge a stone on its own terms before deciding on a setting. Both natural and lab-grown diamonds are offered, with the lab-grown stones described as real diamonds created in a laboratory rather than mined. Advice is available online, by phone or in person at the stores, and the pages are written in German and English.