I’ve never had respectable results using settings on the ‘Default’...
That said, what you have is a good start and I can’t find the specular/glossiness settings, other than playing around with them.
Don’t forget, you need an ‘environment’ for things to look best, otherwise you’ll be reflecting/refracting ‘null space’ and you’ll end up with odd black sections of your glass object.
Yeah, I’ve got a sky-mapped sphere around it for testing, and there’ll be a diner around it in the render. I thought it was DZFire who posted this earlier, but I can’t find it. And I’m still fumbling around with the specular settings — anybody?