How do I make ice cubes that look like the ones in whiskey and spirit advertisements?

You will notice in the pictures of whiskey and spirit advertisements that the ice cubes in the rocks gles are a very unique shape. They look sort of like imperfect cubes. I realize for these commercials that they might use props to look like ice cubes in order to make the drinks look extra good, but still, I would like to use this shaped ice for my drinks.