Thanks for your reply. As far as natural is concerned I have collected it myself. About lab report it easily scratches quartz. It is hexagonal shape and it also has the required specific gravity. I have also posted another pic for your reference.
Are you saying you mined this piece yourself? It looks like it is already pre-formed in your avatar picture. Please post a large picture of the rough with it placed on a piece of paper as your hand is blocking quite a bit of the view. Other than SG, you've done no other testing to eliminate the possibilities? The SG of garnet also falls within the same range as the SG of a ruby. I am inclined to think it could be a garnet due to the hexagonal shape as well.
Ya I have mined it myself. It was found in alluvial deposits that's why it's smooth and looks as if preformed. More over garnets are square notihexagonal.
You are better off going to a site geared towards professionals. While there may be a few of us here who know a little about rough, this site is for consumers, and the focus of the site is on the end product, or cut stones. I will say flat out that no non-Trade member here is qualified to look at pictures of your uncut stone and estimate value. In fact, you will be hard pressed to find a PS member with Trade status to do it as its near impossible to tell anything from photos. There is another website, an online forum largely geared towards those in the business. If you google "online gemology forums" it should be the first site that pops up (we are not allowed to link directly, otherwise I would). The people there will be able to make suggestions on comps you can use to price your rough, assuming that you satisfy all questions and tests to prove that it really is corundum.