In visual arts, the term chiaroscuro refers to the use of strong contrast between lightness and dark.

For Renaissance painters it was a way of alluding to three dimensions on a flat canvas. For the remarkable young Chiaroscuro Quartet, led by Russian violinist Alina Ibragimova, the art of extreme musical shading is deployed as a powerful expressive tool.

The Chiaroscuros play classical repertoire (here Mozart and Schubert) on period instruments. Their sound is svelte, supple and formidably clear, as if layers of excess packaging have been stripped away and the very core of the notes has become audible.

Their technique is impeccable - only players of the highest calibre could risk such an exposed, unadorned approach and make it sound this good - and their unanimous musical intuition makes consistent sense so that every phrase takes the space it needs and every gesture feels natural.

Which isn't to say that their playing is always relaxed, or indeed relaxing. They gave a disquieting account of the Rosamunde Quartet, in which their vivid extremes laid bare Schubert's troubled soul.

The opening theme was so melancholic that its fleeting shift from minor to major came as a radiant shaft of light; the second movement was heartbreakingly understated; the finale's skittish scales ricocheted around with a loaded kind of joviality.

They handled one of Mozart's earliest quartets (K168 in F major) with touching reverence, and one of his later ones (K428 in E-flat major) with searching acumen.

This is still a new-ish group, formed in 2005, but already they play with the breadth and authority of veterans. A stunning Edinburgh debut.