If you are willing to sell a 10 BTC coin for 5 BTC then you might as well peel off the hologram, redeem the BTC on the coin, then send 5 of the 10 BTC you would receive when you redeem the coin to me.

---

Obvious scammer is obvious. I would recommend against dealing with this user....If you do deal with him then you will get scammed and/or waste your time.