The software is Rhino-based- Matrix 3D
http://www.gemvision.com/html/products/matrix/matrix.htmlIt is the gold standard in custom jewelry these days. I am not sure that it is easy- I know someone who has been drawing on CAD for over ten years and he found the program to be very difficult to use- it took him about a year to get proficient with it. My current artist is in the Ukraine- he started with Matrix and he is superb. Jewelry seems to be difficult for most people who have done other kinds of CAD and I am not sure why.
Here are some cufflink drawings and renderings:
These are available in 10K gold, 14K gold, 18K gold, palladium, or platinum.