Varnished, lacquered, plated, or otherwise coloured base metal clasps.
Lobster claw clasps in various colours and sizes.
Clasps which fold closed. These are often quite inconspicuou.
Clasps consisting of two parts which click together.
Electroplated base metal clasps. These can be goldtoned, silvertoned, coppertoned or gunmetal.
Magnetic clasps made of anodized aluminium. These are very easy to close - just bring the halves of the clasp close to each other and they'll click together.