Pure alpha alumina powders have been synthesized under oxidizing or reducing atmosphere. They have been characterized by specific surface area measurements, scanning electron microscopy and X-Ray diffraction. No differences have been detected. However the sintering rate of these powders depends on the synthesis atmosphere. The densification of alumina is accelerated when powders are prepared under oxidizing atmosphere. Only thermoluminescence (TL) analysis differentiated these powders. TL is a physical phenomenon linked to the presence of point defects. This technique consists of measuring the light intensity emitted during the heat of a pre-irradiated solid. The point defects considered are aluminium vacancies and oxygen vacancies. The sintering behaviour is connected to the TL properties. The influence of the atmosphere is discussed in terms of point defects.