I think a normal site can get away with it, if it is done correctly. I developed a site for a jewelry company that uses something similar. But their budget ran out before I could totally implement everything, I only did very limited SEO on the site before they moved the SEO to India (they are an Indian company themselves).
One thing I think can one up Gemvara is the descriptions. Take this description from Gemvara from this page http://www.gemvara.com/jewelry/emerald-cut-lisa-ring-6mm-gem/emerald-cut-emerald-platinum-ring/gfwx9
"This simple solitaire engagement ring is gorgeous for everyday wear and features a single emerald-cut gemstone. It is carefully handcrafted in your choice of gems and metals."
This description is used for every combination of that ring. Which more than likely draws a duplicate content penalty for the other pages (which in itself does not mean that they won't be indexed, it just means they won't be ranked as high). Now lets first look at the Gemvara url and put what we know about SEO in to it. gfwx9, that is meaningless to both you and I, it is no more than trash on the url, just watering it down. Lets look at the structure of the url, sitename.com/jewelry/RINGSTYLE/default-ring-parameters If you notice how the URL for that page works, if you change the style to white gold the url becomes, http://www.gemvara.com/jewelry/emerald-cut-lisa-ring-6mm-gem/emerald-cut-emerald-18k-white-gold-ring/gv3cm so it is safe to lose the trash at the end of the url.
Now for the description, it does not change, the only on site changes are the image, and the selection to the left of the piece. What if you used a variable system similar to how a content spinner worked and changed out words based on the metal or stone selection. I am going to caps the changed out words.
For a Yellow Gold and Diamond
This TRADITIONAL solitaire engagement ring is BEAUTIFUL for everyday wear and features a single emerald-cut DIAMOND. It is carefully handcrafted in SOLID 14KT GOLD.
For a White Gold and Diamond
This MODERN solitaire engagement ring is LONGING for everyday wear and features a single emerald-cut DIAMOND. It is carefully handcrafted in SOLID 14KT WHITE GOLD.
For Platinum and Ruby
This LAVISH solitaire engagement ring is STUNNING for everyday wear and features a single emerald-cut RUBY. It is carefully handcrafted in EXQUISITE PLATINUM.
I have never been known for my writing abilities, but I think you get the drift. I think if you implemented a system like this you would be sure to actually get more pages indexed with combinations than they have. For reference here is the site I was referring to with my short term SEO job. http://vajajewelry.com/women-s-rings/287-the-siren.html One thing, I would consider adding, although I do not like how it is done on this site, is the 360 rotation. This one uses 36 files to make it look smooth, everything is rendered in jewelry cad.