Howard is a great guy who knows and has seen more coticules than any other member here, so his opinion is certainly to be well respected.

" if the stone was greener than the picture" is key. Other than this - there is a difference in smoothness among coticules, and I have had ones from milky to yellow to mustard with a green tinge.

I still don't think this is an Escher - but this shouldn't stop you enjoying it

Cheers
Ivo