Diamonds cut diamonds.

Diamonds cut diamonds.

Turn over a new leaf.

Turn over a new leaf.

Leap out of the frying pan into the fire.

Leap out of the frying pan into the fire.

To cut a whetstone with a razor.

To cut a whetstone with a razor.

To say that which is instructive and also pleasing.

To say that which is instructive and also pleasing.

The coast was clear.

The coast was clear.

To give importance to trifling matters.

To give importance to trifling matters.

To have a smattering knowledge of anything.

To have a smattering knowledge of anything.

With tooth and nail.

With tooth and nail.