JTV may be a good place for you depending on your answers. Approaching your collecting as a business is smart. Overall, JTV is a good place to start as you build information and shape your goals. They are generalists. Just like with stocks or other financial investments, do your homework and research the stones you want to buy beforehand.
The JTV designs are commercially accessible, so if offered at the right price, they will sell. Also, since all the receipts are intact, why not contact JTV and see if there would be any recourse.
About 3 yrs ago for about 3 months, I tried to purchase a Tanzy from JTV. All of different carat weights and cuts. Needless to say, it was a hot mess!!! I spent so much money on returns fees because everytime I received a stone, it wasn't the color they "claimed" it to be!! In one case, I ordered a Trillion and you couldn't tell which side was the pavillion, that's how poor the cutting was ...
JTV would not be my first choice of gemstone vendors. Now this is not to say that they are not reliable, but rather that I have suppliers which I prefer for many reasons, including (but not limited to) ongoing trade relationships with them.
Here's a good way to deal with JTV (and other TV gem places): watch them to see new types of stones that you might not be aware of. If there's something that really interests you, and you see a cheap one, buy it so that you can see what they look like in hand (the quality might not be great, but at least you'll know whether you like the qualities of stone). At the same time, learn about the ...