Edit: Now after reading the whole "customer service will not restore item" thing, i'm going to have to say this is complete BS and needs to get resolved. There are a TON of claims of peoples items just missing and gone when they log in. You cannot continually blame account hacking or accidental loss on some of these.
Edit 2: Keep this post alive and bumped because of how hard you or someone you know worked for the POS staff.
Edit 3, Update: Still no ticket response. Just farmed all the items again, except for the pattern that the BS still has learned and i'm not buying the bell just yet. Actually I have liquid rainbow x2 luckily enough. Not sure what to do at this point..... make a new one? Doubt it. Probably going to sit on the mats and wait until blizz does/says A N Y T H I N G. On another note, I noticed I lost the item when i changed difficulties, and alot of people said the same, so i'm contempalting on creating it in nightmare, upgrading it in nightmare and staying in nightmare, to see if that works.
Edit 4: thanks for the blue post and correction of the post itself. Blues please give us an update of the actual issue when possible
but then again it might be better to not log in for 2-3 months.............