Steel – it’s not the first metal that springs to mind when thinking of jewellery. An alloy of iron and carbon, its use is primarily industrial, relied upon for its tough yet malleable strength. But mixed with the finest quality diamonds? While steel is non-precious, its use in settings that contrast dramatically with the whitest diamonds prove that it’s the treatment of a material that creates a preciousness; if handled with the same level of craftsmanship as gold or platinum, steel is more than a worthy match to the stones it holds. Jewellery writer Jessica Diamond looks at seven highlights from the Sotheby’s Diamonds Steel Collection.