The cap of Cortinarius lucorum is usually grayish brown with a hint of purple. It starts out round, before becoming convex or flat. It is about 3-7 centimeters in diameter. The stipe is approximately 6-7 centimeters long and 0.7-1.4 centimeters wide. It is fibrillose, and has a cortina. The gills are adnate and purplish to brownish in color, and the spore print is rusty brown.