Diachrysia chryson, the scarce burnished brass, is a moth of the family Noctuidae.

It is found in central and southern Europe (including the southern part of the British Isles), Asia Minor across the Palearctic to Japan.

Forewing brownish fuscous tinged with purple: lines dark brown, inconspicuous; inner line waved, oblique inwards; median line visible only at costa; a large subquadrate shining brassy blotch beyond cell between veins 7 and 3, the space between it and inner margin suffused with deep golden brown, both traversed by the fine outer line, which becomes lustrous towards inner margin ; submarginal line very obscure, waved, limiting the brassy and brown patches; hindwing pale bronzy fuscous, darker towards termen.

Larva green; dorsal line darker green, white-edged; some oblique whitish lateral stripes; spiracles white.

The moth flies from July to August depending on the location.