THIS IS THE 10 YEAR ANNIVERSARY OF THE GEMHORN DRAGON
I drew the first one, Dayma, back in 1997
http://silverdragondesign.com/archive/1997/97-11.jpg
(yep, here it is)
and now, 10 years later, I've worked on it and defined it as a species, rather than what it used to be
(it used to be 'any dragon with a gem-like horn.. I've of course, elaborated since)

So's you all know, this is an 'open species'
As long as you give me credit, or heck, just link back to the ref, you are more than welcome to create a Gemhorn of your own.
Because I'm still fine-tuning things, feel free to ask me questions so I can work on straightening things out. Otherwise, enjoy and have fun!

Details here:
http://armaina.deviantart.com/art/Gemhorn-Dragon-Species-Ref-62666629