Children born with some hair colors may find it gradually darkens as they grow.

Clouds broke across the nose; then the sky was baby blue, gradually darkening.

They sat over their coffee in the sitting-room, watching the evening pale and then darken gradually.

As you spend time inside the building, the badge gradually darkens.

The pupa is green at first, gradually darkening to black.

The fruit is dark green, gradually darkening with maturity.

He listened to their story gravely, with a gradually darkening and distressful face.

As summer approaches they darken gradually to a soft brown.

At the touch of a button the windows gradually darken until they are completely blacked out.

The world gradually darkened and night became a certainty instead of a threat.