I agree with the advice posted here so far. The following is just my opinion, so please don't be offended. As a lapidary hobbyist my priority is on buying from a reputable dealer. If I can't see the rough or specimen with my own eyes then I have to trust the dealer's description, cutting evaluation and honesty since it's very difficult to accurately judge the value of rough by electronic images. Specimens are slightly easier to judge, but still not easy in my opinion. If you're planning to rely on pictures to market your inventory then you may need to study the science and art of photographing minerals and gemstones. Casual point and shoot photos without text including expert assessment of cutting implications immediately tells me the dealer doesn't know what goes into crafting a gem from rough. Even the best of the best have a hard time representing gems and gem rough with a camera and film, and in my opinion digital images presented on an LCD or OLED screen are even more challenging.
To sell your "raw gems" you'll need to either take your stock to the buyers in person (shows and such), make it easy to return if they don't like it (without penalties or hassles) by mail order, or else get very, very good at telling the buyers what they need to know accurately. Really it's a matter of trust that the price is fair for the material quality, and that I'm not going to waste what little time I have on problems I didn't bargain for. If I'm paying for mine run in bulk lots then I expect a lot of mostly worthless rocks with only the occasional gem mixed in. Mine run yields vary and I try to factor that into the price I'm willing to pay. Buying individual stones from a mine run lot can thus become an exercise in gambling without reliable information from the seller. Subtle nuances that don't photograph well and / or can easily be disguised by "artful" photographs can dramatically alter the value of a piece of rough. I always feel really dumb and resentful when I think I was tricked into paying gemstone prices for rocks that should only be tumbled, but a fair price for the same stuff marketed as tumbling grade is quite exciting and could easily be a bargain.
For that very reason I never buy from a new supplier over the internet or by mail (now). I did that once on eBay and gained a lot of experience from that. As the saying goes, experience is what you get when you don't get what you want. I do buy over the internet or by mail from an experienced dealer that can prove their credibility and integrity through clear, honest, timely, knowledgeable and helpful (accuracy implied) communications. The word choices in the advertisement are also one way I judge the experience of the seller.