A stone comes with this concrete lamp by Bucharest designer Dragos Motica so the user can smash the shade to reveal the reinforcing steel mesh (+ movie).

Designed for Romanian furniture brand UBIKUBI, the Slash Lamp comes in a cardboard poster tube with a cork cap that, when moved, reveals a small rock.

Unpacking further reveals the lamp itself, which Dragos Motica made from birch plywood, an LED bulb and a reinforced concrete shade encased in concrete.

The user has the choice to leave the lamp as they find it, or use the rock to smash away chunks of the concrete to expose the wire mesh and light bulb within.

"By breaking the lamp you are becoming the designer of a unique object," Motica told Dezeen.

"By leaving it unbroken, you choose the serialised object because you like it as it is. So you are taking a very subjective decision."

The lamp is suspended from the ceiling by a textured cord, attached to a carabiner and spool to enable its height to be adjusted.

"The materials are inspired by industrial facilities, construction sites, rope climbing, and spool for high voltage wires," said the designer. "My goal was to use very common and cheap materials. By doing so, I question the final product's value – its meaning to the user."

"Another reason for using concrete was the aesthetic of filtered light passing through broken reinforced concrete," he added.

The lampshade is produced by pouring concrete into a silicone mould and over the wire mesh. Once set, the concrete form is then air dried and polished smooth.

A cork core cut on a computer numerically controlled (CNC) machine can be inserted into the concrete shape to protect the light bulb when the concrete is smashed.

The Slash Lamp was presented at Romanian Design Week 2014 in May.

Photography is by Bogdan Botofei.