An apparent loss of separation occurred when required hand offs were not accomplished. The reporter suggested different color coding procedures to identify the facility that accepted the hand off.

Narrative

I was working an Air Carrier climbing to 16;000. The aircraft had not yet checked on the frequency. I attempted to climb him to 17;000 and put that altitude in the Data Block and did not get a response. Almost immediately the Conflict Alert went off and I learned that a SF34 was transiting my airspace without a point out. I called Approach to ask if they had the hand off; and they did. I called Sector A to ask if they knew of the plane. They said they got a point out from Sector B. I called Sector B and asked about the plane and the Controller was just relieved and didn't know anything about the plane. Recommend color coding hand offs in the third line of the Data Block to a different color than yellow when an aircraft hand off is taken by an Approach Control versus a Center sector. This is the second instance of this occurring in a week. A better scan of the data block would be prudent to ensure the correct sector took the hand off. If ERAM is delayed; host should be programmed to force a data tag to a sector that is being violated if the sector did not take a point out or does not have the hand off