Diana Model-2 Variant.
From John Griffiths:
Looking at the Diana pistols section, there is another variant of the Model 2 that could be added -one that I only found out about fairly recently. This is characterised by a dark walnut chequered grip with NO ridges around the edge, unlike the relatively common post-war gun with a light (beech?) wood grip that has both chequering and ridges. As the former is marked "Made in West Germany" and the latter "Made in Germany" it is reasonable to assume that the walnut grip version came first after the war, before German reunification.
I have only come across a handful of these guns - and only one in the UK and the rest in Germany, which suggests that few were imported here. I assume that any intended for the UK market would have been marked "Original", but those I know of all have the Diana name.
Here is a pic of an example: