Since the calibration curve IntCal also reports past atmospheric 14 C concentration using this conventional age, any conventional ages calibrated against the IntCal curve will produce a correct calibrated age. This is due to the fact that the AMS instrument has to be calibrated, and yet the organic materials used for calibration that are supposed to be so old they shouldn't have any detectable radiocarbon left in them all contain so much radiocarbon that it means samples of unknown age can't yield dates above this radiocarbon barrier. When a date is quoted, the reader should be aware that if it is an uncalibrated date a term used for dates given in radiocarbon years it may differ substantially from the best estimate of the actual calendar date, both because it uses the wrong value for the half-life of 14 C, and because no correction calibration has been applied for the historical variation of 14 C in the atmosphere over time. But the radiocarbon detected in diamonds is equivalent to ages of up to 80, years. So you can see why the various age limits have appeared in different publications of ours.