Fake mineral (and fossil) specimens have been around as long as there have been collectors and widely regarded as a big "no-no" for most people, and rightly so.
Some fakes are obvious; I remember well back in 2003 at Ste Marie the open air Romanian guys with their "biro" beryls and masses of vivid pink rhodochrosite. All great until there was a sudden thunderstorm, and the "pink" was transferred to the pavements and puddles!
The specimen pictured above was in Warren Taylor's collection and came a selection of 2 or 3 of these items all presented in his main "museum" display cases.
Warren's point was that although were "fake" the diamonds are reattached to the kimberlite, the association is natural and the chances of finding diamonds naturally attached are very slim.
His other point was that even though the diamonds are comparatively large and good - mounting a 5mm loose crystal on pin is not going to be very eyecatching or informative.
If you are going to mount something on a pin, why not mount it on the rock it came from? At least you some context.
This was not Warren's idea as he bought the specimens "made-up" at Bultfontein in the 1970s.
His recollection that at the time these were readily available at outlets around the mine.
All in all it is a pretty good diamond!