It could be argued that you are taking a photo of the sculpture and therefore have creative input that way, which works for items and scenes that are not a copyrighted art piece, but not for Windstones. The subject of your photo is still copyrighted no matter how nice your photo is.
Most people who use DA don’t actualy read the Terms of Service. Every time you post something to DA though, you are agreeing to the terms of service. The TOS of DA covers what Nam said above. Quote from DA TOS:
” Individuals who have posted works to deviantART are either the copyright owners of the component parts of that work or are posting the work under license from a copyright owner or his or her agent or otherwise as permitted by law. You may not reproduce, distribute, publicly display or perform, or prepare derivative works based on any of the Content including any such works without the express, written consent of deviantART or the appropriate owner of copyright in such works.”
In other words, even if you take a nice photo of something you purchased, unless you have expressed permission from the copyright owner, it’s against the DA TOS to uplaod it to the website.
Each company that makes and sells things is different. Some are more laxed, some fall under “fair use”, some offer their items or images as ‘stock’ which is a permission to use in other artforms.
But like Nam pointed out, in this case Windstone holds ownership and we have permission to post the pyo’s we paint as collaborative artwork on DA, but not the production pieces.
Now, I’m not posting this to point fingers at any one or stomp on any ones idea here. This is only for clarification and informing.
I do very much like the DA pyo group and I love seeing photos of peoples collections and items on the forum here.