It depends on the cut and how white the stone faces up (if there's fluorescence making the stone appear more like an "H", it may be more desireable). A quick search revealed stones in the 3.4-3.5 range were going for around $8600 WITH the PS discount. So, even if it's an amazing cut and faces up extremely white I wouldn't expect to pay more than about $10000--online. At a local B&M store, this may be a "fair" price. Hopefully an appraiser will respond!