Diamond hones are made from very small, industrial grade, diamonds adhered to the face of a metal or plastic plate. Also, because Diamonds are so much harder than any of the other sharpening materials, they tend to cut very fast and last much longer than the other whetstone materials. But, they are also often more expensive to purchase. In addition, Diamond Stones generally consist of three different styles consisting of a solid metal plate coated with an adhesive and diamond dust with holes in the plate to allow the swarf to escape, a solid plate without holes for sharpening tools with corners that might catch in the holes, and a plastic plate with islands of exposed plastic interspersed with the adhesive and diamond dust to act as a lubricant.
Choose the style of stone. You'll need to choose a natural or synthetic stone that can be used wet (soaked in water), with oil, or dry. There are also diamond stones that are actually very small diamonds attached to a metal surface. Stones that are soaked in water are softer stones which means you can quickly sharpen your knives. Unfortunately, these stones will wear down faster than the others. Oil stones are the least expensive and they're made of a harder material.
It looks like it can be a Sci-Fi film prop. This is a 2 stage type of sharpening system. You'll get a non slip cushion with it which is at the bottom offering stability for the user. It's ergonomic handle provides a comfortable and easy grip. This cushion offers the stability needed when sharpening and polishing your pocket knife to it's absolute razor sharpness. The sharpener does the work as you hold down the grip and simply place your pocket knife to get sharpened by the motions of the ceramic and diamond sharpener wheels. Simply run your dull knives through the device and you'll get the results you've been looking for. This one will definitely help you when you learn how to sharpen a pocket knife on the Priority Chef.