Pete,
George raises two good points about wood choice and sales.
I think the verdigris wax on the walnut gives a completely different effect to Gwilym's vase. The green (with the darker background) looks more Emerald in colour - or is that just an effect of the photo. The rim effect with the beads bounding the spiral effect also works for me, giving a visual impact and texture.
But I think the almost mirror like finish of the bowl section is the balance to the darkness of the wood, the fact that it reflects the ambient light, so giving lighter spots as reflections, lightning the overall effect.