Ceramic pencils? Not quite – rather: pencil-shaped ceramic reeds. This is the Anya Pencil Shavings diffuser. I assume that ‘pencil shavings’ in the product name is a reference to the smell as one of the ‘notes’ of the diffuser oil is cedar.
The image has been taken from the Selfridges website. I believe that the use of these images falls under “fair dealing” as described by the UK Copyright service.