Diamonds can scratch glass and in the past were used to leave dated signatures on windowpanes to register that the scratcher had been there, for instance, the window from Shakespeare’s birthplace shown here.

There are instances in literature as well – in Wuthering Heights Lockwood is taken to a room that Heathcliff wants to be left empty. Before going to bed, he finds three names carved into the window—Catherine Earnshaw, Catherine Heathcliff, and Catherine Linton.

Size P / P 1/2

 Natural black diamond crystal; grey diamond beads; 18 carat gold