Here’s a message posted to the Liverpool PHILOS listeserv. Having spend quite a bit time of being obsessed by the grue puzzle, I find this message very interesting.


Dear all,

I spent the last six months researching the emerald market, and in the process discovered some interesting facts that bear on the history of ‘grue’, which is held by many to be an absurd example. I have no use for them at present, so I make them public with the small request that, if you do use this example, you reference this email. It is important to remember when reading the following that Nelson Goodman was also an art dealer and knew the antiques market well.

Emeralds before 1963 had to contain Chromium, or they were not–by definition–emeralds. After the discovery of green beryl in Africa that contained Vanadium, the US jewellery industry redefined “emerald” to mean deep green beryl containing either Chromium or Vanadium. This was done purely for financial reasons. Most US jewellers today no longer know that this happened.

As near as I can tell, this change was never accepted in the UK, nor on the continent. But I am not yet sure of this point.

Vanadium “emeralds” (vemeralds, for short) are bluer than Chromium emeralds (genuine emeralds in my view), and this led to a shift in the definition of emerald green–in the US–away from spectral green towards bluish green.

One could argue that of the emeralds on the market, only the Columbian Chromium emeralds are genuine, and I suspect that they represent a small fraction of what is sold as emerald in the US. (Though once again, in the 19th c., what we now call green beryl was called emerald.) They are green, as opposed to bluish-green.

So, grue is real, it can cost you $$’s or ££’s: if you own a grue vemerald, as is most likely the case if you bought your vemerald in the US and Canada, it is probably not worth what you paid for it.


David Hyder