While the type of gemstone here is unspecified, the lone star-shaped rock placed right in this picture's middle is very striking. The crystal appears to pop out of the screen, and its multicoloured facets tilt and twist in a direction dictated by whatever reflections of light manifest on them. Having a shadow beneath the rock, as well as the white background, further adds to the intrinistic harmony and balance between different parts of the rock. So the purpose is clear - to highlight the beauty of transparent and translucent gemstones - and this piece succeeds with flying colours at delivering just that.
Though this is intended to be an "étude" or study work, it has sufficient merits to make it fit for display in a real art gallery. Soft strokes are employed to give the crystal a more "natural" feel while maintaining the dazzling power of its points. Even the reflections of light do not extend all the way to the edges, emphasising the irregular form by having dark edges on the outside and light ones on the inside. Furthermore, it is easy to see the light rays are coming from above the rock.
As for the exact nature of this "étude" work, this is really novel and definitely worth savouring.