This is not as hard as you may think.  Even if you are an amateur, you still need to do your Homework!  Research, prior to any purchase.  It really does matter what type of medium was used to create the carving.  Make sure, what you are purchasing is really what you will be receiving.  Example:  If the items are a semi-precious stone, make sure this is a true statment.  There are so many "Want-to-Be" stones that are just fake as a final product.  Take (Howlite); A white color stone that can be color changed to appear as Turquoise, Jasper, and even Lapis.  Adventurine (Quartz family) has been passed of as Jade.  Again "Do Your Homework"! Use the Internet!  Ask Questions!  Don't just buy because the price is right, and then item is wrong.  Please don't leave bad feedback  if you purchased something and did not ask questions first.   99.99% of the sellers on E-bay attempt to provide the best information available on what they are selling.  It is the .01% that makes it hard for the others.   It is the .01% that you always hear about.   Good luck and have fun.  Visit often, Bid often, Buy often.

JW Owner