Class Change Bug - Inventory

Upon changing classes from Crusader to Demon Hunter, one of my recently acquired legendary gems (Jade 3*, rank 2) disappeared from my inventory. A prior version of the same gem (Jade 2*, rank 2) reappeared in my inventory even though I had destroyed it as part of upgrading my Jade 3* to rank 2. In addition to the bug being fixed, I need the item returned, especially considering what Bliz charges for platinum needed to buy gems on the market.

Blizzard sent a support and they sent me to the forum to solve my problem. So about 2 days ago a gem of mine 4/5 disappeared from my inventory because I was saving gems to be able to level it. It’s called gem called mournful and it was marketable. Please help me.